Regression in unpack for minimal int value

### Description

The following code:

```php
<?php
var_dump($a=-2147483648, bin2hex($b=pack("i",  $a)), unpack("i", $b));
```

Resulted in this output:
```
  int(2147483648)
```

But I expected this output instead:
```
  int(-2147483648)
```
See https://3v4l.org/3pTU9 and efe79e0de6944091b585293210667976c23006d7


### PHP Version

8.1.2RC1

### Operating System

irrevelant