Fix the perpetual haste cheat.

Rogue V3 allowed the player to gain perpetual haste by quaffing a
potion of haste while already hasted.  This is supposed to remove the
haste effect and cause temporary paralysis.

Super-Rogue removed haste correctly, but gave confusing messages.

rogue3/misc.c

@@ -320,20 +320,23 @@ chg_str(int amt)
  *	add a haste to the player
  */
 
-void
+bool
 add_haste(int potion)
 {
     if (on(player, ISHASTE))
     {
 	msg("You faint from exhaustion.");
 	no_command += rnd(8);
+	player.t_flags &= ~ISHASTE;
 	extinguish(nohaste);
+	return FALSE;
     }
     else
     {
 	player.t_flags |= ISHASTE;
 	if (potion)
 	    fuse(nohaste, 0, rnd(4)+4, AFTER);
+	return TRUE;
     }
 }