operator_array_new_with_dtor_left_oob: turn opt back on

unlike __attribute__((optnone)) MSVC's #pragma optimize("", off)
needs to be turned back on

Author: barcharcraz

compiler-rt/test/asan/TestCases/Windows/operator_array_new_with_dtor_left_oob.cpp

@@ -13,7 +13,9 @@ struct C {
 __attribute__((optnone))
 #endif
 int ATTRIBUTE_NOINLINE hide(int x) { return x; }
-
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma optimize("", on)
+#endif
 int main() {
   C *buffer = new C[42];
   buffer[hide(-(1 + (int)sizeof(void*) / 4))].x = 42;