Merge third_party/smhasher/src from https://chromium.googlesource.com/external/smhasher.git at 6f63a4882e6b2cf87e8eec1a3ef8644e0d963283

This commit was generated by merge_from_chromium.py.

Change-Id: Iad27471ee24ed16659190bc72ebb1f10748a990c