rumpuser_clock_sleep
int rumpuser_clock_sleep(int, int64_t, long);
rv = rumpuser_clock_sleep(RUMPUSER_CLOCK_RELWALL, sec, nsec);
rumpuser_clock_sleep(RUMPUSER_CLOCK_RELWALL, 10, 0);
error = rumpuser_clock_sleep(RUMPUSER_CLOCK_ABSMONO,
rumpuser_clock_sleep(RUMPUSER_CLOCK_RELWALL,