Remove dependency on SkRasterPipeline from SkOpts.

The only thing SkOpts actually needed to know was the number of RP
ops, and this is conveniently factored out into a separate header now.

Change-Id: I41b8ff58cf4f702baa280fd18a0461b95784cf8c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/630756
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Herb Derby <herb@google.com>
5 files changed