Merge r205010 from head to stable/8:

Merge r205010 from head to stable/8:

  Update nfsrv_getsocksndseq() for changes in TCP internals since FreeBSD 6.x:

  - so_pcb is now guaranteed to be non-NULL and valid if a valid socket
    reference is held.

  - Need to check INP_TIMEWAIT and INP_DROPPED before assuming inp_ppcb is a
    tcpcb, as it might be a tcptw or NULL otherwise.

  - tp can never be NULL by the end of the function, so only check
    TCPS_ESTABLISHED before extracting tcpcb fields.

  The NFS server arguably incorporates too many assumptions about TCP
  internals, but fixing that is left for another day.

  Reviewed by:		bz
  Reviewed and tested by:	rmacklem
  Sponsored by:		Juniper Networks

Approved by:	re (kib)

git-svn-id: svn://svn.freebsd.org/base/stable/8@208769 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f