[Bug go/66574] Time is provided in millisecond precision instead of nanoseconds as described in go documentation

[ian at airs dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66574

--- Comment #7 from Ian Lance Taylor <ian at airs dot com> ---
I'm a little worried because I'm not 100% confident that clock_gettime is
available in the standard library on all systems.  I don't want to break GCC 5
is that is the case.  Admittedly I haven't seen any bug reports on mainline
yet, but it's only been a few days.