Fix skia_use_gl = false build

Fix a number of warnings as errors about unused private methods when
skia_use_gl is set to false and SK_GL is not set.

Change-Id: Idcc08a1434ec11a6ce9c8df034c9fa472bf08d08
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/436822
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
1 file changed