replace gInited with SkOnce

The bug was originally about TSAN failures on Mac,
but we might as well also fix _win.

Bug: skia:7187
Change-Id: I086060c9f6719afbb6b0a067a9601b6abcc29d78
Reviewed-on: https://skia-review.googlesource.com/61300
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
1 file changed