replace SkOpts::hash_fn

This new version always delivers the same results,
and I think can be simplified like this without
spoiling any of the bulk speed.

Change-Id: I20e42e58418e658278bb5db9472c39722b33160a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/338339
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
2 files changed