[Bug libstdc++/93421] futex.cc use of futex syscall is not time64-compatible

[bugdal at aerifal dot cx]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93421

--- Comment #7 from Rich Felker <bugdal at aerifal dot cx> ---
Indeed, the direct clock_gettime syscall stuff is just unnecessary on any
modern system, certainly any time64 one. I read the patch briefly and I don't
see anywhere it would break anything, but it also wouldn't produce a useful
Y2038-ready configuration, so I don't think it makes sense. Configure or
source-level assertions should just ensure that, if time_t is larger than long
and there's a distinct time64 syscall, the direct syscall is never used.