[NETFILTER]: nf_conntrack_netlink: transmit mark during all events

The following feature was submitted some months ago. It forces the dump
of mark during the connection destruction event. The induced load is
quiet small and the patch is usefull to provide an easy way to filter
event on user side without having to keep an hash in userspace.

Signed-off-by: Eric Leblond <eric@inl.fr>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>