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

[john.salmon at deshaw dot com]

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

--- Comment #1 from John Salmon <john.salmon at deshaw dot com> ---
Created attachment 46727
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46727&action=edit
demonstration code