[php-src] Issue #20802: Segfault when bad type SNI_server_cert passed in

Issue: https://github.com/php/php-src/issues/20802
Author: dixyes

### Description

server:

```php
<?php

$context = stream_context_create([
    'ssl' => [
        'SNI_enabled' => true,
        'SNI_server_certs' => [
            'localhost' => false, // not a string/array
        ],
    ],
]);

$stream = stream_socket_server('tls://0.0.0.0:12443', $errno, $errstr, STREAM_SERVER_BIND | STREAM_SERVER_LISTEN, $context);

$conn = stream_socket_accept($stream);
```

connect with:

```bash
openssl s_client -debug 127.0.0.1:12443
```

missing check here:

https://github.com/php/php-src/blob/434b14e4a3001c3b23607df0c80478d72e4ac2c8/ext/openssl/xp_ssl.c#L1435-L1437

### PHP Version

```plain
master
```

### Operating System

_No response_