Description:
------------
ZIP archives may contain files with an empty filename[1]:

| If input came from standard input, the file name length is set
| to zero.

If such a file is extracted, there is a memory leak.  The same
happens whenever virtual_file_ex() fails for the given filename,
for whatever reason.

[1] <https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT> section 4.4.12


Test script:
---------------
<?php
$zip = new ZipArchive();
$zip->open(__DIR__ . "/test.zip", ZipArchive::CREATE|ZipArchive::OVERWRITE);
$zip->addFromString("", "yada yada");
mkdir(__DIR__ . "/extract");
$zip->open(__DIR__ . "/test.zip");
$zip->extractTo(__DIR__ . "/extract", "");
?>


Actual result:
--------------
[Thu Sep 30 13:42:44 2021]  Script:  'C:\php-sdk\phpdev\vc15\x64\zip1.php'
ext\zip\php_zip.c(154) :  Freeing 0x0000023abbe88000 (1 bytes), script=C:\php-sdk\phpdev\vc15\x64\zip1.php
=== Total 1 memory leaks detected ===