Replace SkOpts::hash/hash_fn with SkChecksum::Hash32

- Two places were computing two 32-bit hashes (with different seeds).
  Instead, just compute a single 64-bit hash.

Change-Id: I935599a257312ba0df1ebf14847481953e608861
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/701523
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Herb Derby <herb@google.com>
34 files changed