ext/date: Pack php_interval_obj

This reduces the size of the struct from 88 to 80 bytes.

ext/date/php_date.h

@@ -89,9 +89,9 @@ static inline php_timezone_obj *php_timezone_obj_from_obj(zend_object *obj) {
 struct _php_interval_obj {
 	timelib_rel_time *diff;
 	int               civil_or_wall;
+	bool              initialized;
 	bool              from_string;
 	zend_string      *date_string;
-	bool              initialized;
 	zend_object       std;
 };