[graphite] Add Debug Graphite build to CQ.

We've gotten far enough along that I don't want changes in main Skia to
start breaking Graphite.

Bug: skia:12466
Change-Id: I66cf2e889521382ef51a99e0966d239f841da655
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/456462
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
2 files changed