ctdb-tcp: Mark node as disconnected if incoming connection goes away

ctdb-tcp: Mark node as disconnected if incoming connection goes away

To make it easy to pass the node data to the upcall, the private data
for ctdb_tcp_read_cb() needs to be changed from tnode to node.

RN: Avoid marking a node as connected before it can receive packets
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14084

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
Autobuild-User(master): Martin Schwenke <martins@samba.org>
Autobuild-Date(master): Fri Aug 16 22:50:35 UTC 2019 on sn-devel-184