Update: Use status_signal instead of status_thread.

Update: Use status_signal instead of status_thread.

The status_thread is being used specifically for the signal thread.
Change the standard practice to have this renamed to status_signal.

This then helps make other status names make more sense.
Rather than have status_thread, status_thread_a, and status_thread_b, instead have status_signal, status_a, and status_b.