fixed -Werror build failure in 32-bit arches
fixed -Werror build failure in 32-bit arches

Change-Id: I72513fdc29dc1e787141015d2d99a0c5715d28d1
Reviewed-on: http://review.couchbase.org/12613
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

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