osd: skip peer_info on down osds
osd: skip peer_info on down osds

We don't clean old/down OSDs out of peer_info map, since we may not
restart peering when strays go up/down.  That's fine... just make sure
we ignore them later.

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph