[php-src] Issue #20622: integer overflow in ImageString

Issue: https://github.com/php/php-src/issues/20622
Author: chongwick

### Description

The following code:

```php
<?php
$im = imagecreate(100, 30);

$bg = imagecolorallocate($im, 255, 255, 255);
$textcolor = imagecolorallocate($im, 0, 0, 255);

imagestring($im, 5, 2147483647, 0, 'Hello world!', $textcolor);
```

Resulted in this output:
```
/home/w023dtc/nightly_php/php-src/ext/gd/gd.c:3020:7: runtime error: signed integer overflow: 2147483647 + 9 cannot be represented in type 'int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/w023dtc/nightly_php/php-src/ext/gd/gd.c:3020:7
```



### PHP Version

```plain
nightly
```

### Operating System

ubuntu 22.04