Add a new command to 'lpc' called 'setstatus', which would be used to

Add a new command to 'lpc' called 'setstatus', which would be used to
change the status message of a print queue.  This includes some minor
changes to the upstat() routine, so that error messages are not printed
while seteuid(priv-user).

Reviewed by:	freebsd-audit and freebsd-print@bostonradio.org
MFC after:	10 days