Add the missing return statements from revision 241399.

llvm-svn: 241405
diff --git a/clang/lib/Headers/altivec.h b/clang/lib/Headers/altivec.h
index 61ad320..37e695f 100644
--- a/clang/lib/Headers/altivec.h
+++ b/clang/lib/Headers/altivec.h
@@ -3712,14 +3712,15 @@
 }
 
 /* vec_mul */
+
 static vector float __ATTRS_o_ai vec_mul(vector float __a, vector float __b) {
-  __a * __b;
+  return __a * __b;
 }
 
 #ifdef __VSX__
 static vector double __ATTRS_o_ai
 vec_mul(vector double __a, vector double __b) {
-  __a * __b;
+  return __a * __b;
 }
 #endif