When iterating a list of queued_items make sure to do it by reference
When iterating a list of queued_items make sure to do it by reference

Change-Id: I93a4cce079397b40b6c36865bbc8c1cef028d4c6
Reviewed-on: http://review.couchbase.org/43489
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>
Tested-by: Michael Wiederhold <a17fed27eaa842282862ff7c1b9c8395a26ac320@couchbase.com>

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