Revert of Introducing the LLVM greedy register allocator. (patchset #10 id:410001 of https://codereview.chromium.org/1061923005/)

Reason for revert:
Breaks Static Initializers test.

http://build.chromium.org/p/client.v8/builders/V8%20Linux64/builds/3210/steps/Static-Initializers/logs/stdio

Original issue's description:
> Introducing the LLVM greedy register allocator.
>
> This change aims to introduce the separation of the RegisterAllocator model,
> using the initial prototype for RegisterAllocatorGreedy as proof of concept.
>
> Summary:
> - new flag, turbo-greedy-regalloc, enabling the new allocator. Default
>   false.
> - separated RegisterAllocator into a base type and two derived,
>   RegisterAllocatorLinear (the one currently used in TurboFan) and
>   RegisterAllocatorGreedy (the new one).
> - initial, untested impementation for the greedy allocator.
>
> BUG=
>
> Committed: https://crrev.com/ec542dea6b6a0cb82d1578a389569d019a59121d
> Cr-Commit-Position: refs/heads/master@{#28015}

TBR=dcarney@chromium.org,titzer@chromium.org,jarin@chromium.org,jvoung@chromium.org,mtrofin@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1080953006

Cr-Commit-Position: refs/heads/master@{#28017}