Revert of MIPS: Enable v8 compilation with CLANG. (patchset #1 id:1 of https://codereview.chromium.org/1519493002/ )

Reason for revert:
[Sheriff] This seems to break chromium runhooks for android:
https://build.chromium.org/p/client.v8.fyi/builders/Android%20Builder/builds/1794

Original issue's description:
> MIPS: Enable v8 compilation with CLANG.
>
> Updated toolchain.gypi to support v8 using CLANG on MIPS. These changes
> include using integrated assembler with CLANG, and disabling options
> used by GCC which are not supported by CLANG.
>
> TEST=
> BUG=
>
> Committed: https://crrev.com/0bae3c393575de4503cb179faa220e597e35dd8f
> Cr-Commit-Position: refs/heads/master@{#32780}

TBR=paul.lind@imgtec.com,akos.palfi@imgtec.com,balazs.kilvady@imgtec.com,ivica.bogosavljevic@imgtec.com,jkummerow@chromium.org,Ilija.Pavlovic@imgtec.com,Ilija.Pavlovic@imgtec.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1520823002

Cr-Commit-Position: refs/heads/master@{#32781}