This cl moves color and coverage off of drawstate.  In an effort to keep this CL manageable, I have left the compute invariant input / output in a bit of a strange state(fixing this will be complicated).

In addition, NVPR makes this very complicated, and I haven't quite figured out a good way to handle it, so for now color and coverage DO live on optstate, but I will figure out some way to refactor that in future CLs.

BUG=skia:

Review URL: https://codereview.chromium.org/783763002
diff --git a/src/gpu/GrSoftwarePathRenderer.h b/src/gpu/GrSoftwarePathRenderer.h
index 620e00b..226cb35 100644
--- a/src/gpu/GrSoftwarePathRenderer.h
+++ b/src/gpu/GrSoftwarePathRenderer.h
@@ -36,6 +36,7 @@
 
     virtual bool onDrawPath(GrDrawTarget*,
                             GrDrawState*,
+                            GrColor,
                             const SkPath&,
                             const SkStrokeRec&,
                             bool antiAlias) SK_OVERRIDE;