[Bug c++/107500] Useless atexit entry for ~constant_init in eh_globals.cc

[rdiezmail-gcc at yahoo dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107500

--- Comment #20 from R. Diez <rdiezmail-gcc at yahoo dot de> ---
I had to modify the patch slightly. I guess that union member "unsigned char
unused;" was removed after GCC 12.2 was released.

But otherwise, the patch does work, at least in my bare-metal scenario. The
atexit entry is no longer being generated, and I haven't seen any other
side-effects yet.