Description:
------------
According to official documentation on https://www.php.net/manual/en/locale.lookup.php, Locale::lookup will return the given $default if no match is found. This usually works as expected, unless if the given $locale is 157 characters long, or more. Then the $default seems entirely ignored.

I expect that Locale::lookup will always return the $default, whatever the length of $locale might be.

PHP versions were the bug were confirmed:

```
$ php8.0 --version
PHP 8.0.9 (cli) (built: Jul 30 2021 13:03:39) ( NTS )
Copyright (c) The PHP Group
Zend Engine v4.0.9, Copyright (c) Zend Technologies
    with Zend OPcache v8.0.9, Copyright (c), by Zend Technologies
    with Xdebug v3.0.4, Copyright (c) 2002-2021, by Derick Rethans
```

```
$ php7.4  --version
PHP 7.4.22 (cli) (built: Jul 30 2021 13:08:17) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
    with Zend OPcache v7.4.22, Copyright (c), by Zend Technologies
    with Xdebug v3.0.4, Copyright (c) 2002-2021, by Derick Rethans
```

```
$ php7.2  --version
PHP 7.2.34-23+ubuntu20.04.1+deb.sury.org+1 (cli) (built: Jul  1 2021 16:07:07) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.2.34-23+ubuntu20.04.1+deb.sury.org+1, Copyright (c) 1999-2018, by Zend Technologies
    with Xdebug v3.0.4, Copyright (c) 2002-2021, by Derick Rethans
```

Extract of `php8.0 -i` that might be relevant:

```
intl

Internationalization support => enabled
ICU version => 66.1
ICU Data version => 66.1
ICU Unicode version => 13.0

Directive => Local Value => Master Value
intl.default_locale => no value => no value
intl.error_level => 0 => 0
intl.use_exceptions => Off => Off
```

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

// Expect to see "fr", but get null
var_dump(Locale::lookup(["fr"], str_repeat("a", 157), false, "fr"));

Expected result:
----------------
I expect to get the given default locale of "fr"

Actual result:
--------------
I incorrectly get null