m_useupall

While updating discard_minvent I noticed that m_useupall is using
the wrong routine to get rid of a monster's weapon.  It probably doesn't
matter since I don't think monsters can use up items they're wielding or
wield items they could use up.

src/mthrowu.c

@@ -452,8 +452,8 @@ struct monst *mon;
 struct obj *obj;
 {
 	obj_extract_self(obj);
-	possibly_unwield(mon, FALSE);
 	if (obj->owornmask) {
+	    if (obj == MON_WEP(mon)) mwepgone(mon);
 	    mon->misc_worn_check &= ~obj->owornmask;
 	    update_mon_intrinsics(mon, obj, FALSE, FALSE);
 	    obj->owornmask = 0L;