[krbdev.mit.edu #3423] Add support for utmps interface on HPUX 11.23

[nate.yocom@centrify.com via RT]

HPUX 11.23 now uses yet another new utmp interface, the utmpd daemon -
which is to be accessed via the <utmps.h> header/functions.  Without
support for these functions, the following error occurs when execv'ing
/bin/login from telnetd:

"No utmp entry.You must exec "login" from the lowest level "sh".
     Connection closed by foreign host."

I.e. /bin/login fails because it checks with the utmpd daemon for the
utmp associated with the current session.

The attached patch adds a check for setutsent (the utmps equivalent to
setutent or setutxent), and sets HAVE_SETUTSENT if available. Based on
HAVE_SETUTSENT we then redefine the utmp management macros to use the
utmps interface rather than the older deprecated (on 11.23 at least)
functions.

Thanks,
Nate Yocom
Senior Software Engineer
Centrify Corporation
425.462.5894
www.centrify.com