remove curse vs saddle

Prayer reward can already uncurse a cursed saddle because hero is
stuck on it.  Allow scroll/spell of remove curse to do so too.

The original riding implementation in slash'em operated with the
saddle in hero's inventory rather than in the steed's, so it would
have handled this without any extra effort.  Presumeably that was
overlooked when incorporating riding into nethack changed it to
have saddle be part of the steed's inventory instead of hero's.

src/sit.c

@@ -394,7 +394,9 @@ rndcurse(void)
         if (!Blind) {
             pline("%s %s.", Yobjnam2(otmp, "glow"),
                   hcolor(otmp->cursed ? NH_BLACK : (const char *) "brown"));
-            otmp->bknown = 1; /* ok to bypass set_bknown() here */
+            otmp->bknown = Hallucination ? 0 : 1; /* bypass set_bknown() */
+        } else {
+            otmp->bknown = 0; /* bypass set_bknown() */
         }
     }
 }