SkQP: fix model colorspace (16-bit gold images)

Problem: `make_gmkb.go `was ignoring the ignoring the embedded ICC
profile in the images it was getting from Gold.

Replace make_gmkb.go with two small programs: `` and

`make_skqp_model` uses Skia to create the model from a bunch of images.

`goldgetter` wraps `make_skqp_model` and handles:
  - json parsing
  - downloading images from gold
  - multiprocessing


Change-Id: I7add1a1dfd83bbd0ab07ab126d4183c36325263c
Commit-Queue: Hal Canary <>
Reviewed-by: Mike Klein <>
6 files changed