This is the first of several commits to contribute Linux on z Systems
(s390/s390x) port of V8.  We will be breaking up the changes into several
(hopefully) logical commits.

This commit contains the changes to V8 Makefile and build toolchains to
introduce S390 macros and compiler options.  Just for awareness for reviewers
is that s390 is 31-bit (not 32!) big-endian platform on Linux on z.  (MSB of address
is used to distinguish between 24-bit vs 31-bit addressing!)  s390x is
64-bit Linux on z.  Names follow the general linux convention on the platform.

A quick roadmap on upcoming commits:
- Add \#include of S390 header files in common files
- S390 related tests + tooling changes
- printf macro for printing size_t values.
- S390 platform-specific code generation code (bulk of changes!)

R=danno@chromium.org,svenpanne@chromium.org,michael_dawson@ca.ibm.com,jyan@ca.ibm.com,mtbrandyberry@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1585813002

Cr-Commit-Position: refs/heads/master@{#33304}

Deferring enabling of tests to separate per platform CLs.

R=machenbach@chromium.org,titzer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1553083003

Cr-Commit-Position: refs/heads/master@{#33123}

Revert of Remove wasm compile time option and enable wasm behind a runtime flag. (patchset #54 id:1050001 of https://codereview.chromium.org/1516753007/ )

Reason for revert:
[Sheriff] Some build failures, e.g.:
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20shared/builds/7502

Original issue's description:
> Remove wasm compile time option and enable wasm behind a runtime flag.
>
> R=titzer@chromium.org
> BUG=
>
> Committed: https://crrev.com/153f2bd47cce9d5dfa74074dda34c02731d96924
> Cr-Commit-Position: refs/heads/master@{#32955}

TBR=titzer@chromium.org,bradnelson@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1531073003

Cr-Commit-Position: refs/heads/master@{#32957}

R=titzer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1516753007

Cr-Commit-Position: refs/heads/master@{#32955}

TEST=
BUG=

Review URL: https://codereview.chromium.org/1334793004

Cr-Commit-Position: refs/heads/master@{#31011}

This is so we can build with the flag on in the snapshot.
D8 then needs to be run with --vector-stores.

BUG=
R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/1339593002

Cr-Commit-Position: refs/heads/master@{#30692}

Adding wasm=on when invoking make will build with the wasm prototype, Ex:

make x64.debug wasm=on V=1

BUG=None
TEST=manual
R=titzer@chromium.org,ncbray@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/1293073004

Cr-Commit-Position: refs/heads/master@{#30236}

Nobody seems to use it. A good alternative is rlwrap.

R=jochen@chromium.org

Review URL: https://codereview.chromium.org/1250223002

Cr-Commit-Position: refs/heads/master@{#29810}

Review URL: https://codereview.chromium.org/1225683010

Cr-Commit-Position: refs/heads/master@{#29551}

BUG=chromium:502176
LOG=n

Review URL: https://codereview.chromium.org/1203653002

Cr-Commit-Position: refs/heads/master@{#29245}

The merge makes it possible to reuse variables from the
android configuration in standalone.gypi.

BUG=chromium:502176
LOG=n

Review URL: https://codereview.chromium.org/1196253002

Cr-Commit-Position: refs/heads/master@{#29189}

This should help to keep syntax errors from creeping into v8.h

Also, I'll remove usages of to-be-deprecated APIs and turn this flag on
for standalone builds

BUG=4134
R=vogelheim@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/1149633003

Cr-Commit-Position: refs/heads/master@{#28538}

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1085283002

Cr-Commit-Position: refs/heads/master@{#27852}

BUG=
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/966773005

Cr-Commit-Position: refs/heads/master@{#27055}

Revert "Partially reland Auto-generate v8 version based on tags."

This reverts commit 0707afc8.

Revert "Ensure tags are fetched when generating the V8 version."

This reverts commit ea6831e9.

Revert "Restrict tag-update for version generation to cached git repos."

This reverts commit c6641e13.

BUG=chromium:446166
LOG=n

Review URL: https://codereview.chromium.org/866263005

Cr-Commit-Position: refs/heads/master@{#26244}

This relands parts of
https://codereview.chromium.org/843913009

It prepares for using this script outside of v8, e.g. in a
chromium hook.

The script is intended to run as a hook and will create
version_gen.cc if the content has changed.

Changes to gyp and gn files can land as a follow up, once
calling the hook on the chromium side has landed.

BUG=chromium:446166
LOG=n

Review URL: https://codereview.chromium.org/830093003

Cr-Commit-Position: refs/heads/master@{#26144}

Revert of Temporarily restore make dependencies (patchset #1 id:1 of https://codereview.chromium.org/733203008/)

Reason for revert:
make dependencies is stale now, and everybody should have switched over

Original issue's description:
> Temporarily restore make dependencies
>
> We will remove dependencies in about a week again.
>
> BUG=none
> R=machenbach@chromium.org
> LOG=y

TBR=machenbach@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=none

Review URL: https://codereview.chromium.org/791813007

Cr-Commit-Position: refs/heads/master@{#26134}

Contribution of PowerPC port (continuation of 422063005). The inital patch
covers the core changes to the common files.  Subsequent patches will cover
changes to common files to support AIX and to update the ppc directories so
they are current with the changes in the rest of the project.

This is based off of the GitHub repository
https://github.com/andrewlow/v8ppc

BUG=
R=svenpanne@chromium.org, danno@chromium.org, sevnpanne@chromium.org

Review URL: https://codereview.chromium.org/817143002

Cr-Commit-Position: refs/heads/master@{#26091}

Also make sure that x86_64 is mapped to x64 as target arch

R=machenbach@chromium.org
LOG=n
BUG=none

Review URL: https://codereview.chromium.org/846363002

Cr-Commit-Position: refs/heads/master@{#26052}

R=vogelheim@chromium.org

Review URL: https://codereview.chromium.org/845973003

Cr-Commit-Position: refs/heads/master@{#26029}

All builders that used level 1 should meanwhile define
v8_enable_slow_dchecks, and so they can use level 2 without losing
coverage. Level 2, however, is considerably faster, so we want to use it
on those builders as well. The make optdebug setting is not affected by
this change.

BUG=none
R=machenbach@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/847753002

Cr-Commit-Position: refs/heads/master@{#26019}

The default for the various debug modes doesn't change.

In a follow-up, OptDebug1 and OptDebug2 will be merged

R=machenbach@chromium.org
LOG=y
BUG=none

Review URL: https://codereview.chromium.org/846653002

Cr-Commit-Position: refs/heads/master@{#26015}

Instead, just use DCHECKs. The builders that want them in release mode
should already be useding dcheck_always_on anyways

BUG=none
R=machenbach@chromium.org
LOG=y

Review URL: https://codereview.chromium.org/841083002

Cr-Commit-Position: refs/heads/master@{#26001}

The logic was supposed to trigger a rebuild if the CXX variable is
changed. However, it failed to track the other compiler related
variables, and, what is worse, conflicted with the clang=1 gyp setting
by forcing CXX to g++

The new logic just relies on tracking GYP defines, and checks whether
the CXX binary - if set - has a target different from the host
architecture.

BUG=none
R=jkummerow@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/807143003

Cr-Commit-Position: refs/heads/master@{#25973}

Review URL: https://codereview.chromium.org/791723004

Cr-Commit-Position: refs/heads/master@{#25741}

Revert of Use same blob format for internal and external snapshots. (patchset #2 id:20001 of https://codereview.chromium.org/787033002/)

Reason for revert:
[sheriff] breaks http://build.chromium.org/p/client.v8/builders/V8-Blink%20Linux%2064%20%28dbg%29/builds/1293

Original issue's description:
> Use same blob format for internal and external snapshots.
>
> R=vogelheim@chromium.org

TBR=vogelheim@chromium.org,yangguo@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/792563002

Cr-Commit-Position: refs/heads/master@{#25729}

R=vogelheim@chromium.org

Review URL: https://codereview.chromium.org/787033002

Cr-Commit-Position: refs/heads/master@{#25727}

We will remove dependencies in about a week again.

BUG=none
R=machenbach@chromium.org
LOG=y

Review URL: https://codereview.chromium.org/733203008

Cr-Commit-Position: refs/heads/master@{#25719}

Also remove the now disfunctinal 'builddeps' and 'dependencies' targets

BUG=none
R=machenbach@chromium.org,jkummerow@chromium.org
LOG=y

Review URL: https://codereview.chromium.org/788613002

Cr-Commit-Position: refs/heads/master@{#25710}

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/722613002

Cr-Commit-Position: refs/heads/master@{#25290}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25290 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/694533003

Cr-Commit-Position: refs/heads/master@{#25219}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25219 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

The turbocheck target is similar to quickcheck, but runs only the
turbofan variant.

R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/697573002

Cr-Commit-Position: refs/heads/master@{#25026}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25026 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

BUG=
R=ishell@chromium.org, jkummerow@chromium.org

Review URL: https://codereview.chromium.org/631763003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24419 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

As per discussion on the V8 team, this is the place we want them to live,
not following the Chrome Style Guide for this.

BUG=v8:3489
LOG=y
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/615393002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24350 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/594823002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24148 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

Dependencies were updated in Chromium, see
https://codereview.chromium.org/425333002/ for details.

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/451993002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22984 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

Because Benedikt said so.

BUG=none
LOG=y
R=bmeurer@chromium.org, machenbach@chromium.org

Review URL: https://codereview.chromium.org/434423002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22806 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

Fix r22531, I dropped a necessary pair of parens.

BUG=
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/410003003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22565 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

r22509 fixed arm and mips (big-endian) cross-compilation builds.

It did not fix mipsel, mips64el, or arm64 builds, since the
toolchain prefix did not match the v8_target_arch.

For mips, the toolchain is typically named mips-linux-gnu-g++,
but it can compile for mipsel or mips64el via flags. (There can
also be mipsel-linux-gnu-g++ toolchains, and this patch will
work for mipsel build in that case).

For arm64, the toolchains seem to be named aarch64-linux-gnu-g++.

BUG=
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/408133002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22531 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

BUG=none
TBR=machenbach@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/412503002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22528 ce2b1a6d-e550-0410-aec6-3dcde31c8c00