Don't pass a timeout of 0 ticks to pause() for a delay of less than 1
hz tick.  On 8.x this results in an infinite sleep as pause() does not
support a delay of 0 ticks.  Since all delay values are converted from
nanoseconds to ticks using a floor function, skipping the sleep for a
delay smaller than 1 tick is the more consistent than rounding up to a
single tick.

This is a direct commit to 8 and 9 as 10.x and later use pause_sbt()
instead.

Reviewed by:	avg

(cherry picked from commit 004eeed9b05bf81152f859c7df23281e7d8b43a1)