Add test for GH-14109

Author: iluuu1994

ext/zend_test/tests/gh14109.phpt

@@ -0,0 +1,16 @@
+--TEST--
+GH-14109: User class extending internal class with attributes
+--EXTENSIONS--
+zend_test
+--FILE--
+<?php
+class Test extends ZendAttributeTest {}
+foreach ((new ReflectionClassConstant(Test::class, 'TEST_CONST'))->getAttributes() as $attribute) {
+    var_dump($attribute->newInstance());
+}
+?>
+--EXPECTF--
+object(ZendTestRepeatableAttribute)#%d (0) {
+}
+object(ZendTestRepeatableAttribute)#%d (0) {
+}