rpcrt4: Don't return void values. This fixes Visual C++ warnings.

dlls/rpcrt4/tests/cstub.c

@@ -56,7 +56,7 @@ static void * CALLBACK my_alloc(size_t size)
 static void CALLBACK my_free(void *ptr)
 {
     my_free_called++;
-    return NdrOleFree(ptr);
+    NdrOleFree(ptr);
 }
 
 typedef struct _MIDL_PROC_FORMAT_STRING

dlls/rpcrt4/tests/ndr_marshall.c

@@ -42,7 +42,7 @@ void * CALLBACK my_alloc(size_t size)
 void CALLBACK my_free(void *ptr)
 {
     my_free_called++;
-    return NdrOleFree(ptr);
+    NdrOleFree(ptr);
 }
 
 static const MIDL_STUB_DESC Object_StubDesc =