provide dungeon location in ^X feedback

Dungeon level wasn't included in ^X output, so it wasn't actually
giving all status fields and attempting to rely on it when turning
off 'status_updates' was leaving a gap in feedback for the player.
Add an extra line to the first section where character's name and
patron deity are reported, giving current location.
|You are in the Dungeons of Doom, on level 5.
or
|You are in the endgame, on the Elemental Plane of Fire.

The information is more explicit than the basic status field, but
you can already get similar information via #overview so it isn't
giving away extra info.

src/topten.c

@@ -62,7 +62,6 @@ struct toptenentry {
 
 STATIC_DCL void FDECL(topten_print, (const char *));
 STATIC_DCL void FDECL(topten_print_bold, (const char *));
-STATIC_DCL xchar FDECL(observable_depth, (d_level *));
 STATIC_DCL void NDECL(outheader);
 STATIC_DCL void FDECL(outentry, (int, struct toptenentry *, BOOLEAN_P));
 STATIC_DCL void FDECL(discardexcess, (FILE *));
@@ -178,7 +177,7 @@ const char *x;
         putstr(toptenwin, ATR_BOLD, x);
 }
 
-STATIC_OVL xchar
+int
 observable_depth(lev)
 d_level *lev;
 {