[Bug libgcc/64885] libstdc++ all_attributes failure

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64885

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Ditto the header guards like
GCC_GTHR_POSIX_H
GCC_GTHR_SINGLE_H
GCC_GTHR_H
and macros like
GTHREAD_USE_WEAK
HIDE_EXPORTS