Move existing writeICC() code into SkICC

BUG=skia:

Change-Id: Ifb7db7adcc69104fa9abe1765fd60b7f627bdbaf
Reviewed-on: https://skia-review.googlesource.com/6261
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
3 files changed