Emulate illumos interface cf_timedwait_hires()

Needed for Illumos #3852 and , this interface is supposed to support a
variable-resolution timeout with nanosecond granularity.  This
implementation just rounds up to jiffie resolution, as this was the most
expedient solution, and nanosecond resolution is rarely needed for
real-world performance tuning.

References:
    https://www.illumos.org/issues/3582
    illumos/illumos-gate@0689f76