Add macos condition support for G3 build

Change-Id: I4204b878a6bbf212e53aaf9e2e8cc9a760233d6e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/300173
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed