Comment out unused names in src/core/SkGlyphCache.h

Android violates our encapsulation and depends on this file;
to keep their compiles clean they want us to hide the names
of unused parameters.

Follow-up to https://codereview.chromium.org/726923002/.

R=djsollen@google.com

Review URL: https://codereview.chromium.org/839583005
1 file changed