MFC r281309:

MFC r281309:
  Fix the check for maximum mbuf's size needed to send ND6 NA and NS.
  It is acceptable that the size can be equal to MCLBYTES. In the later
  KAME's code this check has been moved under DIAGNOSTIC ifdef, because
  the size of NA and NS is much smaller than MCLBYTES. So, it is safe to
  replace the check with KASSERT.

  PR:		199304

git-svn-id: svn://svn.freebsd.org/base/stable/10@281866 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f