verif: close down server on sim_term.

Make sure that we've properly disconnected clients and closed down the
socket to avoid TIME_WAIT nastiness.
tests: use fifo notification for waiting for sim activation.

Rather than polling on a connect(), use a named fifo to indicate
readiness, this removes races between connect+disconnect and the real
connect.
debugger: send sim terminate at end of test.

This makes sure that the simulator cleans up properly.