try harder to exclude SkXbyak.cpp from Google3 build

Change-Id: I26ce450e00b0634deeda61815ef6d501e788c0ae
Reviewed-on: https://skia-review.googlesource.com/6700
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
1 file changed