Remove extra semi colon from faiss/index_factory.cpp

Summary:
`-Wextra-semi` or `-Wextra-semi-stmt`

If the code compiles, this is safe to land.

Reviewed By: algoriddle

Differential Revision: D52969102

fbshipit-source-id: f6e4992783a2a1ab0598bf96c664da950e5bba5d

faiss/index_factory.cpp

@@ -216,7 +216,7 @@ VectorTransform* parse_VectorTransform(const std::string& description, int d) {
         return new RemapDimensionsTransform(d, std::max(d_out, d), false);
     }
     return nullptr;
-};
+}
 
 /***************************************************************
  * Parse IndexIVF