gnutls:
 * bump version to [http://lists.gnutls.org/pipermail/gnutls-devel/2013-February/006084.html 2.12.23], by dns + fixes by me
 * fixes #2410


git-svn-id: file:///var/svn/freetz/trunk@11862 149334a1-2f27-0410-a3b9-fc62619ac1e6