Add ProgramKinds for private color filters and blenders.

We need to distinguish between public and private color filters and
blenders, even though they don't have a dedicated module, so we can
determine which programs are allowed to call $private_functions.

Change-Id: If1e2609a96ca05409de0a6611e848b59ce44f75d
Bug: skia:13810
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/591272
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Arman Uguray <armansito@google.com>
9 files changed