add Leon's gradient to p3 GM

Running...

  $ ninja -C out dm
  $ out/dm -m p3 --config 8888 srgb f16 esrgb p3 glp3 glesrgb glf16 -w foo
  $ open foo/*/gm/p3.png

... looks like esrgb and f16 are marked wrong, and all others right,
which points to a problem specific to the software backend.

Bug: skia:8730
Change-Id: Ibffe3014e6ed1ade9c04381530a3c84a690e6469
Reviewed-on: https://skia-review.googlesource.com/c/188028
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
1 file changed