Move cubic cusp existence test into GrStrokeHardwareTessellator.cpp

GrStrokeHardwareTessellator is the only user that needs to simply
check if a cusp exists at all. Making the check local speeds up the
microbench from 502us -> 392.

Bug: chromium:1172543
Change-Id: I52adf9ef0a66e1267435e6ce41f01ee1eda17d7a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/373744
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
6 files changed