Hard reboot with pending threads will crash Dream Daemon

[SpaceManiac]

Possible outcomes:

• Thread is not join()ed - ~thread calls terminate() calls abort()
• Thread is join()ed during global destructor - indefinite hang
• Thread is detach()ed - crash when thread tries to access now-unloaded code or memory

Test case here: https://gist.github.com/SpaceManiac/b23ec263e786c09dc89f0399b97e71fc