s3-smbstatus: display [u|g]id of -1 as "-1" in connection list

s3-smbstatus: display [u|g]id of -1 as "-1" in connection list

In order to avoid displayed uid or gid of "4294967295" instead of "-1", we
need to fetch the special case -1.
The id can be -1 if we are reading e.g. incomplete session information.

Signed-off-by: Björn Baumbach <bb@sernet.de>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Wed Jul 10 01:18:30 CEST 2013 on sn-devel-104