This reverts commit fffa4555.

Reason for revert:
https://build.chromium.org/p/client.v8/builders/V8%20Win32%20ASAN/builds/1905

Original change's description:
> [build] Prepare switching win asan to 64 bits
> 
> This switches the current win32 bots to win32 under the hood in MB. We'll
> remove them and replace them with win64 bots in a follow up on the infra
> side.
> 
> This also infers the clang option from asan, because on windows we need
> to set clang explicitly.
> 
> TBR=sergiyb@chromium.org
> 
> Bug: chromium:786303
> Change-Id: I9dddd5050a21a364c302a761ff15ddd21e97c7dc
> Reviewed-on: https://chromium-review.googlesource.com/883103
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Commit-Queue: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#50828}

TBR=machenbach@chromium.org,sergiyb@chromium.org

Change-Id: I2e17aa6ddf44a03d9da29e8b7f7dd2c9f6fe4cb9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:786303
Reviewed-on: https://chromium-review.googlesource.com/883501Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50829}