clock_getres: don't assume time_t is 32-bit on 32-bit archs

clock_getres: don't assume time_t is 32-bit on 32-bit archs

the time64 syscall for this is not necessary or useful, since clock
resolution is generally better than 68-year granularity. if there's a
32-bit syscall, use it and expand the result into timespec; otherwise
there is only one syscall and it does the right thing to store to
timespec directly.

on 64-bit archs, there is no change to the code after preprocessing.