fix ssh protocol 1 on the server that regressed with the sshkey change
(sometimes fatal() after auth completed), make file return useful status
codes.
add an explicit rwlock around the global state (the pool list and serial
number) rather than rely on implicit process exclusion, splhigh and splvm.

the only things touching the global state come from process context so we
can get away with an rwlock instead of a mutex. thankfully.

ok matthew@
tweak previous;
take the pools mutex when copying stats out of it in the sysctl
path so we are guaranteed a consistent snapshot.
Improve "skipping paragraph macro" messages,
showing which macro was skipped and before or after what.
provide a pool_count global so we can figure out how many pools there are
active without having to walk the global pool_list.
From: Gregor Best
- "delete" works in af inet by default
- priority range is 0 to 15

the "delete" portion tweaked by me
help/ok henning
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.
inline is the new __inline
Use real parameter types for u{dv,vn}_attach() instead of void *

ok guenther