Bugfix: thread exiting issues and related.

Bugfix: thread exiting issues and related.

My attempt to add locks to make helgrind ended up backfired on me.
It seems that when an interrupt is received, the cancel is being sent and it happens at any point in time.
Which includes when locks are opened.
When an interrupt cancels a thread with an open lock, that lock is never closed.
Then, using the same locks to handle cleanup of threads resulted in an occasional deadlock.
Remove all locking in the main thread.
The logic should be safe as the only cases where there might be a conflict, a f_thread_join() is in protected between them.
The cancel function should avoid locks to, where possible.
I am somewhat more nervous about this case, I need to review and confirm if main->thread->processs.size does not change.

I previously updated the force cancel exit thread to use waits and locks.
It later dawned on me that I could just get rid of the force cancel exit thread entirely and implement the same functionality in the cancel thread.