[Bug libstdc++/78968] conflict between gnu's __cxa_thread_atexit and LLVM's/FreeBSD's implementation

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78968

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Created attachment 40448
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40448&action=edit
Check for __cxa_thread_atexit in libc

Does this fix it?