iterative clut()

Code size drops compared to head, and performance is somewhere between
a little better and seriously better, depending on the platform.

Change-Id: I369eaee83d32162f6dcf69efaa2b39c84e17804e
Reviewed-on: https://skia-review.googlesource.com/c/162320
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed