Description:
------------
parent private constant in extends class memory leak

Test script:
---------------
<?php

class FOO
{
    private const FOO = 'BAR';
}

class BAR extends FOO { }

Actual result:
--------------
[Fri Aug 17 01:46:16 2018]  Script:  '/path/to/private_const.php'
/path/to/php-src/Zend/zend_hash.c(140) :  Freeing 0x000000010de6cb40 (288 bytes), script=/path/to/private_const.php
=== Total 1 memory leaks detected ===