Export _Cnd_register_at_thread_exit (DV2AdZFFEh8), _Cnd_unregister_at_thread_exit
(wpuIiVoCWcM) and _Cnd_do_broadcast_at_thread_exit (vyLotuB6AS4), which Minecraft
Legends (PPSA05510) and Rayman 30th (PPSA33016) import.
Registrations live in a process-wide list keyed by the host thread id, as
Microsoft's xnotify.cpp does. The broadcast of the current thread sets the
supplied flag, broadcasts the condition and unlocks the mutex. It runs when a
std::thread exits through _Pad::_Launch and when a title calls _Thrd_exit;
threads created directly with scePthreadCreate are recorded in debt.
