kernel - Fix "cleaned vnode isn't" panic

kernel - Fix "cleaned vnode isn't" panic

* Fix the "cleaned vnode isn't" panic.  This panic was occuring due to
  vrecycle() not checking for a vgone*() recursion.

  Adjust vrecycle() to check for the recursion.  The recursion can be
  detected by testing the VRECLAIMED flag.

* Under certain circumstances hammer_vop_inactive() was calling
  vrecycle().  This could cause the underlying vnode to be modified
  after it has been destroyed as the recursion returns.

* Add a KKASSERT() in vgone_vxlocked() to detect the condition
  earlier if it occurs again.