ctdb-daemon: Implement ctdb_control_startup()

ctdb-daemon: Implement ctdb_control_startup()

This doesn't implement what was recommended.  That would require
careful error handling, probably with a fallback to this code anyway.
This is simple and does no worse that the current code.  That is, the
new node is updated on the next call to tdb_update_tcp_tickles().

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