Description:
------------
When using `php -l` to syntax check a file with stdin (which is how some editors live-check an unsaved file), an error about strict_types declaration not being on the first line is erroneously returned if the file starts with a shebang. This does not happen when passing the filename in directly.

I discovered this using Vim8 with the `ale` linting plugin (w0rp/ale), but it's easily reproduced directly on the command line.

Test script:
---------------
example.php:
```
#!/usr/bin/env php
<?php
declare(strict_types=1);
echo 'hello world';
```

Expected result:
----------------
When linting stdin, the presence of a shebang should not trigger a false positive error:


$ php -l example.php
No syntax errors detected in example.php

$ php -l -- < example.php
No syntax errors detected in example.php


Actual result:
--------------
A false positive is triggered:

$ php -l example.php
No syntax errors detected in example.php

$ php -l -- < example.php
PHP Fatal error:  strict_types declaration must be the very first statement in the script in - on line 3

Executing the file also works fine, as expected:
$ ./example.php
hello world