bring back r1.133. this is a bit different cos we're still using splvm to

bring back r1.133. this is a bit different cos we're still using splvm to
protect pool_list rather than the rwlock that made i386 blow up:

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.