Add test with function pointer

Author: dalg24

libcxx/test/std/atomics/types.pass.cpp

@@ -162,6 +162,7 @@ int main(int, char**) {
   test<std::uintmax_t>();
   test<std::uintmax_t>();
 
+  test<void (*)(int)>();
   test<void*>();
   test<const void*>();
   test<int*>();