ccpr: Don't use flat interpolation when it is slow

Bug: skia:
Change-Id: I1bc087187541183fdbaa5f2b93e8b8d287ac8ef8
Reviewed-on: https://skia-review.googlesource.com/102100
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
8 files changed