[INET_TIMEWAIT_SOCK]: Reorganize struct inet_timewait_sock to save some bytes

/home/acme/git/net-2.6/net/ipv6/tcp_ipv6.c:
  struct inet_timewait_sock |   -8
  struct tcp_timewait_sock  |   -8
 2 structs changed
  tcp_v6_rcv                |   -6
 1 function changed, 6 bytes removed, diff: -6

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>