incorrect return value for atexit/on_exit #734
Description
atexit and on_exit are supposed to return 0 on success, and non-zero on failure.
Currently they return non-zero on failure, and the caller return address on success (since the function returns via jp (hl))
https://en.cppreference.com/w/c/program/atexit
additionally, on_exit functions are supposed to have the value from exit passed into them, but it appears that it is currently a pointer in ram to garbage data, or just directly garbage data if you return from main.