fix #K3436 - crash during restore

triggered by Grayswandir's hallucination resistance.  If the game
is saved while hero is hallucinating but having that be suppressed
by wielding Grayswandir, is riding, and the steed is on an object,
then during restore the hero's location will be updated because
of the presence of the object but the attempt to display the hero
there is made before u.usteed has been restored and fails.

src/display.c

@@ -529,6 +529,20 @@ warning_of(struct monst *mon)
     return wl;
 }
 
+/* map or status window might not be ready for output during level creation
+   or game restoration (something like u.usteed which affects display of
+   the hero and also a status condition might not be set up yet) */
+boolean
+suppress_map_output(void)
+{
+    if (g.in_mklev || g.program_state.restoring)
+        return TRUE;
+#ifdef HANGUPHANDLING
+    if (g.program_state.done_hup)
+        return TRUE;
+#endif
+    return FALSE;
+}
 
 /*
  * feel_newsym()
@@ -562,6 +576,10 @@ feel_location(xchar x, xchar y)
     struct obj *boulder;
     register struct monst *mon;
 
+    /* replicate safeguards used by newsym(); might not be required here */
+    if (suppress_map_output())
+        return;
+
     if (!isok(x, y))
         return;
     lev = &(levl[x][y]);
@@ -721,12 +739,9 @@ newsym(register int x, register int y)
     boolean worm_tail;
     register struct rm *lev = &(levl[x][y]);
 
-    if (g.in_mklev)
+    /* don't try to produce map output when level is in a state of flux */
+    if (suppress_map_output())
         return;
-#ifdef HANGUPHANDLING
-    if (g.program_state.done_hup)
-        return;
-#endif
 
     /* only permit updating the hero when swallowed */
     if (u.uswallow) {