Move GrSwizzle.h from include/private to src/gpu.

Change-Id: I2d992404f540c7f8a1cd5ff633148d92ec50d4fa
Reviewed-on: https://skia-review.googlesource.com/135860
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Auto-Submit: Brian Salomon <bsalomon@google.com>
3 files changed