tests: make no-optimize attribute Clang compatible

test/simple-memory-corruption/uninitialized_free.c

@@ -1,7 +1,8 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "../test_util.h"
+
+OPTNONE int main(void) {
     free((void *)1);
     return 0;
 }