userns: Convert xt_LOG to print socket kuids and kgids as uids and gids
xt_LOG always writes messages via sb_add via printk. Therefore when
xt_LOG logs the uid and gid of a socket a packet came from the
values should be converted to be in the initial user namespace.
Thus making xt_LOG as user namespace safe as possible.
Cc: Pablo Neira Ayuso <pablo@netfilter.org> Cc: Patrick McHardy <kaber@trash.net> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>