LockD: manage used host count per networks namespace

This patch introduces moves nrhosts in per-net data.
It also adds kernel warning to nlm_shutdown_hosts_net() about remaining hosts
in specified network namespace context.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --cc fs/lockd/host.c
Simple merge

diff --cc fs/lockd/netns.h
Simple merge