fix #H4262 - mon weapon attacks for non-weapon dmg

Let monsters who have a weapon attack for non-physical damage dish
out physical damage instead of doing the drain life or drain
strength they usually do if they happen to be wielding cockatrice
corpses or a couple of particular aritfacts that do more harm
than just level drain.  (Other artifacts are candidates, but I
don't think it's worth checking for them since the monsters
involved have such a small chance of acquiring and wielding them.)
Also switch to physical if monster's ability has been cancelled.

Only barrow wight, Nazgul, and erinys are affected.  Yeenoghu and
the Master Assassin have a weapon attack for physical damage and
another one for non-physical damage (not necessarily delivered in
that order).  They haven't been changed--only the physical damage
attack has a chance to apply their weapon's special damage.

doc/fixes36.1

@@ -172,6 +172,9 @@ if a long worm inherited inventory from a previous shape, and if an egg or
 Wizard will now steal any quest artifact from hero, not just own role's
 prevent a hostile renegade Angel of <lawful god> from delivering taunt
 	messages which mention threats of retribution from that god
+a few types of monster (barrow wight, Nazgul, erinys) have weapon attacks that
+	don't deal physical damage, so special damage like stoning via wielded
+	cockatrice corpse wouldn't be inflicted
 
 
 Platform- and/or Interface-Specific Fixes