[Bug libstdc++/95992] chrono adding duration to time_point reports signed integer overflow with -fsanitize=undefined

[redboltz at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95992

--- Comment #2 from Takatoshi Kondo <redboltz at gmail dot com> ---
Thank you.
I understood that I should use appropriate types.
I also understood why libc++ and libstdc++ behavior are different.