[php-src] Issue #21044: make test -j16 yields 9 failed tests

Issue: https://github.com/php/php-src/issues/21044
Author: SvintenDK

### Description

When - on Debian 13 using the vendor-supplied libraries - the following seqeuense yelds 9 errors when making test.

=====================================================================
FAILED TEST SUMMARY
---------------------------------------------------------------------
#66265: gettext doesn't switch locales within the same script [ext/gettext/tests/bug66267.phpt]
Gettext basic test with en_US locale that should be on nearly every system [ext/gettext/tests/gettext_basic-enus.phpt]
Gettext basic test [ext/gettext/tests/gettext_basic.phpt]
Test if bindtextdomain() returns string id if no directory path is set(if directory path is 'null') [ext/gettext/tests/gettext_bindtextdomain-cwd.phpt]
Test dcgettext() functionality [ext/gettext/tests/gettext_dcgettext.phpt]
Test dgettext() functionality [ext/gettext/tests/gettext_dgettext.phpt]
Test if dngettext() returns the correct translations (optionally plural). [ext/gettext/tests/gettext_dngettext-plural.phpt]
Test ngettext() functionality [ext/gettext/tests/gettext_ngettext.phpt]
Bug GH-9259 003 (Setting opcache.interned_strings_buffer to a very high value leads to corruption of shm) [ext/opcache/tests/gh9259_003.phpt]
=====================================================================


[php_test_results_20260126_2327.txt](https://github.com/user-attachments/files/24877247/php_test_results_20260126_2327.txt)

### PHP Version

```plain
root@wpow:~/php-8.5.2# php -v
PHP 8.5.2 (cli) (built: Jan 26 2026 23:59:19) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.5.2, Copyright (c) Zend Technologies
    with Zend OPcache v8.5.2, Copyright (c), by Zend Technologies
root@wpow:~/php-8.5.2#
```

### Operating System

Debian 13