Fix the handling of various counters in the 'core.exit' event listener.  If
the process was exiting due to session initialization, we were failing to
properly decrement the session count.
Minor tweak to the exit_ev handling again; we only want to decrement the
protocol-specific session counters if the session did indeed pass sess_init;
we only want to ALWAYS decrement the daemon-wide connection counter regardless
of sess_init success/failure.