monsters moving after player leaves level

Fix the problem reported by ais where it was possible for one monster
to knock the hero onto a level teleporter (or trapdoor or hole),
destination was selected and allowed-to-level-teleport checks were made,
then for another monster to knock or teleport the not-yet-relocated-hero
onto the Amulet and have auto-pickup move it into inventory.  At the end
of that turn's monster movement, hero would level teleport successfully
despite carrying the Amulet.

This short-circuits monster movement if the hero is scheduled to be
moved to a different level.  The monsters who haven't moved yet don't
lose their pending movement points; they'll catch up if/when the hero
returns to the level.

src/mon.c

@@ -1,4 +1,4 @@
-/* NetHack 3.6	mon.c	$NHDT-Date: 1445556873 2015/10/22 23:34:33 $  $NHDT-Branch: master $:$NHDT-Revision: 1.192 $ */
+/* NetHack 3.6	mon.c	$NHDT-Date: 1446166647 2015/10/30 00:57:27 $  $NHDT-Branch: master $:$NHDT-Revision: 1.193 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -631,12 +631,16 @@ movemon()
      */
 
     for (mtmp = fmon; mtmp; mtmp = nmtmp) {
+        /* end monster movement early if hero is flagged to leave the level */
+        if (u.utotype
 #ifdef SAFERHANGUP
-        if (program_state.done_hup) {
+            /* or if the program has lost contact with the user */
+            || program_state.done_hup
+#endif
+            ) {
             somebody_can_move = FALSE;
             break;
         }
-#endif
         nmtmp = mtmp->nmon;
         /* one dead monster needs to perform a move after death:
            vault guard whose temporary corridor is still on the map */