In commit 1515b91546c42d764e6c4195c8958ff714a02459, superfasthash was replaced with murmurhash3.
You removed superfasthash.h and superfasthash.c, and added murmurhash3.h, but it seems to me that you forgot to add murmurhash3.c...
Thanks, good catch! I didn't noticed this before because local tests were passing (murmurhash.c was not in VCS, but it was in a proper place locally so it gets included to sdist).
In commit 1515b91546c42d764e6c4195c8958ff714a02459, superfasthash was replaced with murmurhash3. You removed superfasthash.h and superfasthash.c, and added murmurhash3.h, but it seems to me that you forgot to add murmurhash3.c...