Calculate and format TCP_COOKIE SYN option.

Create (and destroy) cookie data structures.

This is a significantly revised implementation of an earlier (year-old)
patch that no longer applies cleanly, with permission of the original
author (Adam Langley):

    http://thread.gmane.org/gmane.linux.network/102586

Requires:
   TCPCT part 1c: sysctl_tcp_cookie_size, socket option TCP_COOKIE_TRANSACTIONS
   TCPCT part 1d: define TCP cookie option, extend existing struct's

Signed-off-by: William.Allen.Simpson@gmail.com
---
  net/ipv4/tcp_ipv4.c      |   20 +++++
  net/ipv4/tcp_minisocks.c |   45 +++++++++--
  net/ipv4/tcp_output.c    |  182 ++++++++++++++++++++++++++++++++++++++++------
  net/ipv6/tcp_ipv6.c      |   13 +++
  4 files changed, 228 insertions(+), 32 deletions(-)