Fix HANGUPHANDLING ifdef for TTY

The SIGHUP handling for the TTY windowport added in 594cb5f was wrapped
in '#ifdef HANGUP_HANDLING', but the actual define is 'HANGUPHANDLING'
without the underscore.

win/tty/wintty.c

@@ -69,7 +69,7 @@ extern void msmsg(const char *, ...);
 #define AVTC_SOUND_PLAY    4
 #endif
 
-#ifdef HANGUP_HANDLING
+#ifdef HANGUPHANDLING
 /*
  * NetHack's core switches to a dummy windowing interface when it
  * detects SIGHUP, but that's no help for any interface routine which
@@ -91,10 +91,10 @@ extern void msmsg(const char *, ...);
         if (g.program_state.done_hup)           \
             return (RES);                       \
     } while (0)
-#else /* !HANGUP_HANDLING */
+#else /* !HANGUPHANDLING */
 #define HUPSKIP() /*empty*/
 #define HUPSKIP_RESULT(RES) /*empty*/
-#endif /* ?HANGUP_HANDLING */
+#endif /* ?HANGUPHANDLING */
 
 /* Interface definition, for windows.c */
 struct window_procs tty_procs = {