Revert of GN: support 32-bit x86 builds (patchset #6 id:100001 of https://codereview.chromium.org/2340463008/ )

Reason for revert:
https://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu-Clang-x86-Debug-GN_Android/builds/304

Original issue's description:
> GN: support 32-bit x86 builds
>
> Take over Ubuntu -x86- bots.
>
> Note the change to Build-Win-MSVC-x86-Release-GN.json, which is not incidental.
> We'll want target_cpu="x86" there too.
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2340463008
>
> Committed: https://skia.googlesource.com/skia/+/1949386ae00485ae92dd5608a2614b9dee417542

TBR=jcgregorio@google.com,borenet@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review-Url: https://codereview.chromium.org/2338173004
7 files changed