Add wyhash as SkChecksum::Hash32/64

This is going to replace SkOpts::hash_fn. It's fast, portable, and a
much better hash function than CRC.

Change-Id: I242616548a15ece49c57c7fcd52a21940a8c6c90
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/700226
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
6 files changed