hangup tweaks (trunk only)

hangup tweaks (trunk only)

     Fix a typo in some conditional (NOSAVEONHANGUP) code, and tweak
SAFERHANGUP so that it doesn't defer hangup handling if the game hasn't
started yet or has already finished (it's possible to be waiting for a
--More-- prompt at end of game code before the hangup handler is reset,
so the regular handler could be called in that state).  Also, undefine
SAFERHANGUP if NOSAVEONHANGUP is defined, since there's no point in
deferring hangup for the latter.