Remove docs for macros that don't exist in the code.

Change-Id: Ibabe3f1f9663ec36b5128bdb6f1cfeb7b8e09e8a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/272896
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
1 file changed