Factor out curve-op selection code.

In a followup, this will make it easier to fuse separate R+G+B ops
with identical transfer functions into a single RGB op.

Change-Id: Iada9786ec71da461aaad37be10231f68a10d2cca
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/771527
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
1 file changed