Remove extraneous semicolon from cachelib/common/MurmurHash.h

Summary:
Extraneous semicolons are a code smell and can mask more serious problems. `-Wextra-semi-stmt` finds them.

This diff removes an extraneous semicolon or adjusts a macro so that a semicolon is required after the macro (making it look like a standard function).

This file is drawn from a heavy-hitting list, so fixing this problem will allow *many* other files to take advantage of the safety `-Wextra-semi-stmt` offers.

This should be a low-risk diff: if it compiles, it works.

Reviewed By: meyering

Differential Revision: D51631139

fbshipit-source-id: 0854ead335557d01111f90ebac5b83ba964f351e

cachelib/common/MurmurHash.h

@@ -67,7 +67,7 @@ inline uint32_t murmurHash2(const void* key, int len, uint32_t seed) {
   case 1:
     h ^= data[0];
     h *= m;
-  };
+  }
 
   // Do a few final mixes of the hash to ensure the last few
   // bytes are well-incorporated.