debian/patches: Include patches to support null or empty user name

PAM modules (such as the smart card ones) can find the user name associated to an authentication method automatically, so avoid doing this from pamtester if an invalid name is passed as argument.

Patches are originally from http://git.altlinux.org/gears/p/pamtester.git

Forwarding them upstream doesn't make much sense because upstream seems quite dead for long time.