netfilter: nfmark IPV6 routing in OUTPUT, mangle, NFQUEUE

This patch let nfmark to be evaluated for routing decision for OUTPUT
packet, in mangle table, when process paquet in NFQUEUE. This patch is
an IPv6 port of Laurent Licour IPv4 one.

Signed-off-by: Eric Leblond <eric@inl.fr>
Signed-off-by: Patrick McHardy <kaber@trash.net>