Move SkTHash.h to src/core

It was no longer needed in Recorder.h, which was the only reference from
include/.

Change-Id: I6e32e65d1ccbc3574a93965b671524f29b33395c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/627919
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
89 files changed