trickery bulletproofing

Prevent the pardoning of trickery in wizard mode from attempting
to continue when there's no longer any current level.  Also prevent
the ZEROCOMP configuration from trying to read from file descriptor -1
in case there're any other places which still let that slip through.
And fix an oddity in the VMS port's error() routine which has gone
unnoticed for years.

sys/vms/vmstty.c

@@ -1,4 +1,4 @@
-/*	SCCS Id: @(#)vmstty.c	3.4	1995/07/09	*/
+/*	SCCS Id: @(#)vmstty.c	3.4	2002/08/21	*/
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /* NetHack may be freely redistributed.  See license for details. */
 /* tty.c - (VMS) version */
@@ -477,5 +477,9 @@ error VA_DECL(const char *,s)
 	Vprintf(s,VA_ARGS);
 	(void) putchar('\n');
 	VA_END();
+#ifndef SAVE_ON_FATAL_ERROR
+	/* prevent vmsmain's exit handler byebye() from calling hangup() */
+	(void)signal(SIGHUP, SIG_DFL);
+#endif
 	exit(EXIT_FAILURE);
 }