The socket matching function has some nifty logic to get the struct sock
from the skb or from the connection tracker.
We export this so other xt_* can use it, similarly to ho how
xt_socket uses nf_tproxy_get_sock.
Change-Id: I11c58f59087e7f7ae09e4abd4b937cd3370fa2fd
Signed-off-by: JP Abgrall <jpa@google.com>
d8cfaaaf68