netfilter: xt_socket: added new revision of the 'socket' match supporting flags

If the XT_SOCKET_TRANSPARENT flag is set, enabled 'transparent'
socket option is required for the socket to be matched.

Signed-off-by: Laszlo Attila Toth <panther@balabit.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>