Slim Skia down to just one murmur3 implementation.

Slim Skia down to just one murmur3 implementation.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/6ac0037b70410ff7d5ce5788bc89314223e1a587

Committed: https://skia.googlesource.com/skia/+/67a3271f0de9ccc32d559b042b862528272047cc

Committed: https://skia.googlesource.com/skia/+/53d435990bdb4d14df78013da45a9364d0287ebe

CQ_EXTRA_TRYBOTS=tryserver.skia:Perf-Mac10.6-MacMini4.1-GeForce320M-x86_64-Release-Trybot
R=reed@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/376183004