[Bug libstdc++/91486] future::wait_for and shared_timed_mutex::wait_for do not work properly with float duration

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91486

--- Comment #14 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #13)
> Those are doing exactly what the Networking TS requires.

For that matter, so was our implementation of condition_variable::wait_for that
was changed for bug 68519.