polkit: fix CVE-2013-4288

Integrate community fix for the issue CVE-2013-4288

Signed-off-by: Priyanka Shobhan <priyanka_shobhan@mentor.com>
Merge pull request #205 from pshobhan/pshobhan/bugfix/cve-2013-4288

polkit fix CVE-2013-4288