fix compiler warning

src/routine.c

@@ -46,7 +46,7 @@ static inline zend_result pmmpthread_routine_run_function(pmmpthread_zend_object
 	//fake stack frame to make sure zend_call_function() doesn't swallow exceptions
 	//we need to be able to pass them to the user exception handler if there is one
 	memset(&execute_data, 0, sizeof(execute_data));
-	execute_data.func = &zend_pass_function;
+	execute_data.func = (zend_function*) & zend_pass_function;
 
 	if (pmmpthread_monitor_check(&connection->ts_obj->monitor, PMMPTHREAD_MONITOR_ERROR)) {
 		return result;