PG: choose acting set and newest_update_osd based on a map of all osds
PG: choose acting set and newest_update_osd based on a map of all osds

newest_update osd should be stable when the primary changes, to
prevent cycles of acting set choices. For the same reason, we should
not treat the primary as a special case in choose_acting.

Also remove the magic -1 from representing the current primary.

Signed-off-by: Josh Durgin <51652c783f70f5b272ebd02f1fd20d3af7a2449f@dreamhost.com>

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