Use sk_memset* in GrFillBufferWithColor

Change-Id: I6ead74a61884967f9a60eba614414bc42079d28b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/216343
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed