[ganesh][dawn] Disable derivative uniformity warnings

This disables derivative uniformity analysis in the Ganesh Dawn backend.

Change-Id: I8292943e8adf989a5ff5031c8ef562d03821855a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/658116
Commit-Queue: Arman Uguray <armansito@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
1 file changed