ctdb-killtcp: Filter out sent packets

ctdb-killtcp: Filter out sent packets

When previously killing TCP connections via the daemon there was some
latency due to each kill being sent to the daemon via a separate
control.  This probably meant that when doing a 2-way kill the tickle
ACKs sent to the client end of a connection would not interfere with
listening for the reply ACK from the server end.  Now that there is no
latency, the tickle ACK or RST sent to the client end can be seen as
the reply to the server end tickle ACK, and vice-versa.

To avoid this, throw away packets that look like we sent them.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>