Added some named gamma recognition to lutnType ICC profile parsing

Most CMYK images I tested had linear gamma specified as tables, which
is easily recognized and when present allows an entire SkRasterPipeline
stage to be avoided for every single channel. This is likely due to the
fact that gamma tables are required in lutntype A2B0 profiles.

BUG=skia:

Change-Id: I82b65848c4099035d61098abb66e9afe0b080930
Reviewed-on: https://skia-review.googlesource.com/5388
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Robert Aftias <raftias@google.com>
2 files changed