* libc/stdlib/on_exit_args.{c,h}: New files.
* libc/stdlib/Makefile.am: Add new source file.
* libc/stdlib/Makefile.in: Regenerate.
* libc/stdlib/__atexit.c (__register_exitproc): Initialize
_on_exit_args_ptr field of _GLOBAL_ATEXIT on first run.
* libc/stdlib/on_exit.c: Force linking of static instance of
_on_exit_args.
* libc/stdlib/cxa_atexit.c: Likewise.