soccr: add source and destination addresses to libsoccr_sk_data

These addresses will be used to restore half-closed sockets,
we will need to send a fake fin packet for that.

And in the next patch connect() will be moved into soccr.

Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>