[Bug libstdc++/99327] ENOTSUP macro does not exist on djgpp crt

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99327

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed in my fork:
https://gitlab.com/jonathan-wakely/gcc/-/commit/93847c75473b3509c305e20b60ffe86b120b8e4b