Don't honor vbucket state while doing backfill from disk.
Don't honor vbucket state while doing backfill from disk.

For each item backfilled from disk, we should look up its latest
value in memory hashtable regardless of its vbucket state, and
then send the value in memory if exists to the destination.

Change-Id: I803dc996dbda1cbd231037372d305949bbad79f8
Reviewed-on: http://review.couchbase.org/11661
Reviewed-by: Michael Wiederhold <a17fed27eaa842282862ff7c1b9c8395a26ac320@couchbase.com>
Tested-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

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