Add setter API for willReadDstColor FP flag.

Change-Id: I734a91a1497f9b2fe8abcc572c7f60509bb043bd
Bug: skia:12080
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/417977
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2 files changed