Fix issues encountered in google3 roll.

We need to avoid accidental G3 path rewrites, and ensure that our
types are always properly forward-declared (in a C friendly way).

Change-Id: Ic81087bc6f99636b441c35351844aa7df10dc7b2
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/774816
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Florin Malita <fmalita@google.com>
2 files changed