[Bug libstdc++/103726] --disable-hosted-libstdcxx (freestanding C++) does not provide <coroutine> as what standard requires

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103726

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #2)
> cppreference is wrong, <coroutine> is not freestanding.

I've fixed it now.