bad weapon check for monster multi-shot shooting

bad weapon check for monster multi-shot shooting

A typo caused the bow and arrow check when a monster was wielding an
elven box to test the hero's weapon with monster's ammo.  [I looked
at the old slash'em code where I think this came from and it doesn't
have the typo but does have a different bug.  A monster could get a
multi-shot volley by wielding an elven bow when throwing darts or
spears.  The extra bow and arrow check is intended to prevent that.
The typo was probably by me but I have no memory of that code....]

Elves with bows (or other monsters who manage to pick up and wield an
elven bow) will shoot bigger volleys after this fix.  That will make
them more dangerous but also cause them to run out of arrows more
quickly.