Add missing call to GC_ADDREF() for function attribute hash table

This is required to correctly free the hash table in a later commit.

Author: TimWolla

Zend/zend_compile.c

@@ -1047,6 +1047,12 @@ ZEND_API void function_add_ref(zend_function *function) /* {{{ */
 
 		ZEND_MAP_PTR_INIT(op_array->run_time_cache, NULL);
 		ZEND_MAP_PTR_INIT(op_array->static_variables_ptr, NULL);
+	} else {
+		ZEND_ASSERT(function->type == ZEND_INTERNAL_FUNCTION);
+
+		if (function->common.attributes) {
+			GC_ADDREF(function->common.attributes);
+		}
 	}
 
 	if (function->common.function_name) {