use pool_count to report the number of pools to userland rather than walking the list and counting the elements as we go.
use pool_count to report the number of pools to userland rather
than walking the list and counting the elements as we go.

use sysctl_rdint, sysctl_rdstring, and sysctl_rdstruct instead of
handcrafted copyouts.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars