Deletion of profiles on logout (#6297) added a LocalBackend.Start()
call within setClientStatus(), but that's a callback from the
controlclient. Start() ends calling back into the controlclient (to
shut it down), and we end up stuck in a deadlock waiting for the
authDone channel to be closed.
Fixed by making the Start call asynchronous. To reproduce this in a test
case, we need to do an asynchronous logout, so add a CLI option for
that.
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
2244cebf73