Redundant semicolon added to a file when fixing PSR2.Files.ClosingTag.NotAllowed

Consider the following file:
```php
<?php
/*
 * Some comment goes here
 */
?>
```
Fixing it using `phpcbf --standard=PSR2 test.php` makes it look like:
```php
<?php
;/*
 * Some comment goes here
 */
```
The semicolon is needed to address #773 but it's only needed when there is something else than whitespace or comment after the opening `<?php` tag.