make sure each sample() call uses the same uniforms

As written each sample() call uses its own uniforms,
which amplifies register pressure immensely, especially
for repeat, mirror, and bicubic.

Change-Id: I13043c4cdea530defe79dbf4b66201f2b2f8c3f4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/264475
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed