MB-5418 Fix to the race in updating the non-resident item count.
MB-5418 Fix to the race in updating the non-resident item count.

When a given non-resident item is soft-deleted, the non-resident
item count is decremented. Therefore, we should not decrement the
counter again when we receive SET mutation for that soft-deleted
non-resident item.

Change-Id: Idb8c51e9e9ef66dda975471d687842dba584859b
Reviewed-on: http://review.couchbase.org/17285
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>
Tested-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

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