Add unaffectedByDstValue() to GrProcessorSet::Analysis

This will allow us to decide whether we need a stencil test when
drawing strokes.

Bug: skia:10419
Change-Id: Ie6aa0e4c4af6302c3ec28f9515cfae0e5c41a4ec
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/340517
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
7 files changed