Make destcolor GM non-Ganesh-specific

Change-Id: If133f68f3f199607b7dfd912c0655e5c5510929a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/701401
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: James Godfrey-Kittle <jamesgk@google.com>
1 file changed