missed ZVAL_DEREF for PHP 7.2

[youngvan]

Here is the code to reproduce error:
`<?php

$data = array (
0 => 'test me hard'
);

$xlBook = new \ExcelBook(null, null, true);
$xlBook->setLocale('UTF-8');
$xlSheet1 = $xlBook->addSheet('Sheet1');

var_dump($data);
array_walk($data, function(&$field) {
$field = (string)$field;
});
var_dump($data);

$xlSheet1->writeRow(0, $data);
`

I have posted it here https://bugs.php.net/bug.php?id=76343

and got answer

This is a bug in the extension, which does not support references. Please file a bug there, it's missing a ZVAL_DEREF() in the array processing function.