Fix an error on AIX by using a proper cast.

Objects/methodobject.c

@@ -180,7 +180,7 @@ meth_hash(a)
 		if (x == -1)
 			return -1;
 	}
-	y = _Py_HashPointer(a->m_ml->ml_meth);
+	y = _Py_HashPointer((void*)(a->m_ml->ml_meth));
 	if (y == -1)
 		return -1;
 	x ^= y;