Allow memory tracking to be disabled with an env var
Allow memory tracking to be disabled with an env var

Set EP_NO_MEMACCOUNT=1 to disable memory accounting.

Change-Id: I93364193a67526d500d5f3e7267ab3d18339e41d
Reviewed-on: http://review.couchbase.org/15535
Tested-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

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