ICC:  SkICCGetColorProfileTag supports special cases

Special cases:
  - "sRGB"
  - "AdobeRGB"
  - "DCI-P3"
  - "Linear Transfer with sRGB Gamut"
  - "2.2 Transfer with sRGB Gamut"
  - "sRGB Transfer with DCI-P3 Gamut"
  - "Linear Transfer with DCI-P3 Gamut"
  - "sRGB Transfer with Rec-BT-2020 Gamut"
  - "Linear Transfer with Rec-BT-2020 Gamut"

tools/colorspaceinfo now prints out the Tag.

Also: constants representing gSRGB_TransferFn, g2Dot2_TransferFn, and
gLinear_TransferFn, gDCIP3_TransferFn.

BUG=skia:6720
Change-Id: I92a3f9db9d744d3ec366e4e59afd759ba043c235
Reviewed-on: https://skia-review.googlesource.com/20225
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
6 files changed