[Bug libstdc++/92798] -fshort-enums can break iterators of std::map

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92798

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
We could add an enumerator that forces sizeof(_Rb_tree_color) == sizeof(int),
which would be valid for C++98.