__cxa_atexit() registers a function to be called by exit or when a shared library is unloaded.
The __cxa_atexit() function is used to implement atexit(), as described in ISO POSIX (2003). Calling
__cxa_atexit(func, NULL, NULL)
__cxa_atexit() is not in the source standard; it is only in the binary standard. atexit() is not in the binary standard; it is only in the source standard.