Use steady_clock instead of high_resolution_clock.
Use steady_clock instead of high_resolution_clock.

This is strongly recommended by Howard Hinnant (the designer of C++11
<chrono> and one of the original libc++ implementers); see
https://stackoverflow.com/questions/37426832/what-are-the-uses-of-stdchronohigh-resolution-clock .

ulfjack/ryu,ulfjack/ryu,ulfjack/ryu,ulfjack/ryu