Update example output in getfilename.xml (#5250)

* Update example output in getfilename.xml

This doc has been inaccurate since the release of PHP 5.3.

- PHP 5.2x: https://3v4l.org/iMEHH#v5.2.17
- PHP 5.3: https://3v4l.org/iMEHH#v5.3.0
- Recent PHP versions: https://3v4l.org/iMEHH

Author: eexit

reference/spl/splfileinfo/getfilename.xml

@@ -56,8 +56,8 @@ var_dump($info->getFilename());
 <![CDATA[
 string(7) "foo.txt"
 string(7) "foo.txt"
-string(0) ""
-string(7) "svn.php" 
+string(11) "www.php.net"
+string(7) "svn.php"
 ]]>
     </screen>
    </example>