[GIT-PULLS] [php-src] PR #23338: Fix wrong argument number in fsockopen/pfsockopen timeout error

Pull Request: https://github.com/php/php-src/pull/23338
Author: lacatoire

`php_fsockopen_stream()` called `zend_argument_value_error(6, ...)` for the `$timeout` parameter, but `$timeout` is the **5th** argument. Because `get_function_arg_name(func, arg_num)` returns `NULL` when `arg_num` exceeds the actual argument count, the error message reported the wrong number and dropped the parameter name.

Before:
```
ValueError: fsockopen(): Argument #6 must be -1 or between 0 and 4294967295
```
After:
```
ValueError: fsockopen(): Argument #5 ($timeout) must be -1 or between 0 and 4294967295
```

The same fix applies to `pfsockopen()`, which delegates to the same internal helper.

A regression test is included; it does not require network connectivity since the `ValueError` is raised before any connection attempt.