Don't use analytic clip FPs when drawing to stencil

It doesn't make sense to multiply by coverage when drawing to stencil.
This could theoretically work with FPs that discard and/or modify
the sample mask, but for the time being an analytic FP means one that
calculates a coverage value.

Bug: skia:7190
Change-Id: I44140a5823f8683ec08244bdf9d369f51fa05dd9
Reviewed-on: https://skia-review.googlesource.com/68362
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/gn/gpu.gni b/gn/gpu.gni
index 185d6d8..c364c29 100644
--- a/gn/gpu.gni
+++ b/gn/gpu.gni
@@ -177,6 +177,7 @@
   "$_src/gpu/GrShape.h",
   "$_src/gpu/GrStencilAttachment.cpp",
   "$_src/gpu/GrStencilAttachment.h",
+  "$_src/gpu/GrStencilClip.h",
   "$_src/gpu/GrStencilSettings.cpp",
   "$_src/gpu/GrStencilSettings.h",
   "$_src/gpu/GrStyle.cpp",