remove unused SkImageEncoderFns bits

  - remove a couple transform_scanline_procs
  - remove all use of SK_RESTRICT
  - remove the color table
  - reformat arguments etc.

Change-Id: I545dc6d74fffc7d95e3d53fb26ee748b94f93b65
Reviewed-on: https://skia-review.googlesource.com/c/167683
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
4 files changed