Fix dynamic func def persist with preloading

If we find an existing serialization of the op_array, of course
we also need to actually make use of it...

ext/opcache/zend_persist.c

@@ -704,6 +704,7 @@ static void zend_persist_op_array(zval *zv)
 		}
 	} else {
 		/* This can happen during preloading, if a dynamic function definition is declared. */
+		Z_PTR_P(zv) = old_op_array;
 	}
 }