[Bug libstdc++/110357] [C++26] P2592R3 Hashing support for std::chrono value classes

[dangelog at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110357

--- Comment #1 from Giuseppe D'Angelo <dangelog at gmail dot com> ---
I have posted a preliminary patch, but it needs a rebase and more work
(basically some implementation design choice).