Add compaction times histogram to kvtimings
Add compaction times histogram to kvtimings

Change-Id: I255d0f66f38f8cf748903c992c85960430d1b29a
Reviewed-on: http://review.couchbase.org/34197
Reviewed-by: Sundararaman Sridharan <52fd5d4a6dc39f24404c4ccfbc872fa0f3bb41e2@gmail.com>
Tested-by: Sundararaman Sridharan <52fd5d4a6dc39f24404c4ccfbc872fa0f3bb41e2@gmail.com>

owendCB/ep-engine,jimwwalker/ep-engine,owendCB/ep-engine,teligent-ru/ep-engine,sriganes/ep-engine,jimwwalker/ep-engine,sriganes/ep-engine,daverigby/kv_engine,jimwwalker/ep-engine,daverigby/kv_engine,daverigby/kv_engine,couchbase/ep-engine,daverigby/kv_engine,couchbase/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,hisundar/ep-engine,membase/ep-engine,hisundar/ep-engine,owendCB/ep-engine,sriganes/ep-engine,sriganes/ep-engine,membase/ep-engine,couchbase/ep-engine,membase/ep-engine,jimwwalker/ep-engine,membase/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,hisundar/ep-engine,daverigby/ep-engine,couchbase/ep-engine,daverigby/ep-engine,teligent-ru/ep-engine,owendCB/ep-engine,hisundar/ep-engine