Add new env vars to pylint plugin
The vars api.env.host_princ and smb_princ where introduced a while ago.
Sometimes parallel linting complain about the attributes. Add both to
the list of known members in pylint_plugins.py.
Related: https://pagure.io/freeipa/issue/3999
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>