OSD: move backfill_request_timer cleanup to OSDService::shutdown

Signed-off-by: Samuel Just <sam.just@inktank.com>
OSD: rename timer to tick_timer

Only used for scheduling ticks - we should keep it
that way.

Signed-off-by: Samuel Just <sam.just@inktank.com>
OSD: lookup_lock_raw_pg is dead

Signed-off-by: Samuel Just <sam.just@inktank.com>
OSD: must always check for is_stopping after locking osd_lock

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

Reorder teardown:
- pgs
- queues/threadpools
- persist superblock
- filestore
- timers
- messengers

Signed-off-by: Samuel Just <sam.just@inktank.com>
ceph_osd: clear client_throttler prior to putting g_ceph_context

Signed-off-by: Samuel Just <sam.just@inktank.com>
FileJournal: quieter debugging on journal scanning

Signed-off-by: Samuel Just <sam.just@inktank.com>
shared_cache: clear lru in destructor

Otherwise, the live references will attempt to extricate
themselves from a disolving SharedLRU instance as the
member destructors run.

Signed-off-by: Samuel Just <sam.just@inktank.com>
FileStore::stat: valgrind: don't read *st on error

Signed-off-by: Samuel Just <sam.just@inktank.com>
OpRequest: use OpRequestRef for OpHistory

Signed-off-by: Samuel Just <sam.just@inktank.com>
OSD: clear OpHistory on shutdown

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