Add Win Clang x86 builds.

Enable /arch:SSE2 for Win x86 builds (both MSVC and Clang).

Change-Id: I0618e938b6542b60fae3947b7e0dcde22650ba54
Reviewed-on: https://skia-review.googlesource.com/56721
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
4 files changed