[Bazel] Separate OS and CPU dimensions in Skia sources.

Patching from internal cl/171888276.

No-Try: true
Change-Id: I6919769ad4e367ded394f1094944cea2b3901fd0
Reviewed-on: https://skia-review.googlesource.com/60583
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
1 file changed