monster polearm usage (trunk only)

monster polearm usage (trunk only)

     From newsgroup discussion, reproduced with current dev code (the
missing capitalization is a post-3.4.3 buglet):

  The orc tries to wield a halberd.
  the orc's bow is welded to her hand!
  The orc thrusts a halberd.  You are almost hit by a halberd.

Caused by overloading polearm attacks with throwing.  The monster throwing
code didn't enforce that a polearm must be successfully wielded.