MFC 209029

MFC 209029

 3 Fixes -
 a) There was a case where a ICMP message could cause
    us to return leaving a stuck lock on an stcb.
 b) The iterator needed some tweaks to fix its lock
    ordering.
 c) The ITERATOR_LOCK is no longer needed in the freeing
    of a stcb. Now that the timer based one is gone we don't
    have a multiple resume situation. Add to that that there
    was somewhere a path out of the freeing of an assoc that
    did NOT release the iterator_lock.. it was time to clean
    this old code up and in the process fix the lock bug.

Approved by: re (bz)

git-svn-id: svn://svn.freebsd.org/base/stable/8@209067 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f