common/WorkQueue: remove qlock, unnecessary (squash)

Signed-off-by: Samuel Just <sam.just@inktank.com>
common/WorkQueue: s/QueueInWQ/C_QueueInWQ (squash)

Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedPG: s/QueueInWQ/C_QueueInWQ (squash to workqueue commit)

Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedPG: is_missing implies is_degraded (squash)

Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedPG::dump_recovery_info: s/PGBackend/pg_backend (squash)

Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedPG: remove noop C_OSD_CompletedPull

Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedPG::wait_for_missing_object: s/pulling/recovering

Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedBackend::handle_pull_response: use list<ObjectContextRef>

Signed-off-by: Samuel Just <sam.just@inktank.com>