test: add test for class_alias with reserved name 'resource'

Add regression test to verify that class_alias() rejects 'resource' as
a class alias name since it is a reserved keyword in PHP.

Author: jordikroon

Zend/tests/class_alias/gh16665_3.phpt

@@ -0,0 +1,8 @@
+--TEST--
+GH-16665 (\resource should not be usable)
+--FILE--
+<?php
+class_alias('stdClass', 'resource');
+?>
+--EXPECTF--
+Fatal error: Cannot use "resource" as a class alias as it is reserved in %s on line %d