[IPV6]: Reorg struct ifmcaddr6 to save some bytes

/home/acme/git/net-2.6/net/ipv6/mcast.c:
  struct ifmcaddr6 |   -8
 1 struct changed
  igmp6_group_dropped  |   -6
  add_grec             |   -3
  mld_ifc_timer_expire |  -18
  ip6_mc_add_src       |   -3
  ip6_mc_del_src       |   -3
  igmp6_group_added    |   -3
 6 functions changed, 36 bytes removed, diff: -36

ipv6.ko:
 6 functions changed, 36 bytes removed, diff: -36

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