It was already ported to use libulog, which makes it simpler now. Be
sure to catch the error returned by setutxdb(). Otherwise it may perform
a lookup on the utx.active database.
Unfortunately it also uses lastlog, which means we must resort to local
extensions of the utmpx-interface. Because the user name and TTY name
are now nul-terminated, there is no need to copy around strings as
often.
