Revision 356623

MFC r354643:

  netinet*: update *mp to pass the proper value back

  In ip6_[direct_]input() we are looping over the extension headers
  to deal with the next header.  We pass a pointer to an mbuf pointer
  to the handling functions.  In certain cases the mbuf can be updated
  there and we need to pass the new one back.  That missing in
  dest6_input() and route6_input().  In tcp6_input() we should also
  update it before we call tcp_input().

  The merge is extracted of a larger change in head.

  PR:			240135
  Reported by:		prabhakar.lakhera gmail.com