clearing no_charge bit for containers

[I can't get access to my mail at present, but `cvs update' shows
that there aren't any patch notification messages pending for me.]

     Extend a pre-3.4.3 fix--for objects picked up in an untended shop--
to container contents.  Without it, dropping a bag or box in a tended shop
and declining to sell it, then picking it back up after the shop has become
untended (shk killed or evicted) would leave the contents with no_charge
set.  After that it could be sold in another tended shop, picked back up
for free, then kept or sold a second time.  (Picking it back up in the
tended shop would clear the bit; afterwards it behaved normally.  And it's
not something prone to abuse; if you can make a tended shop become untended
you really don't need to sell stuff twice.  But it'd be noticeably wrong if
anyone ever stumbled across it.)

src/invent.c

@@ -299,8 +299,11 @@ struct obj *obj;
 
 	if (obj->where != OBJ_FREE)
 	    panic("addinv: obj not free");
-	obj->no_charge = 0;	/* not meaningful for invent */
-	obj->was_thrown = 0;	/* ditto */
+	/* normally addtobill() clears no_charge when items in a shop are
+	   picked up, but won't do so if the shop has become untended */
+	obj->no_charge = 0;	/* should not be set in hero's invent */
+	if (Has_contents(obj)) picked_container(obj);	/* clear no_charge */
+	obj->was_thrown = 0;	/* not meaningful for invent */
 
 	addinv_core1(obj);
 #ifndef GOLDOBJ