Error on warnings for gc-couchbase

Change-Id: I10498c8d6c83715eb0f10332cbe129b7617b19a4
Reviewed-on: http://review.couchbase.org/41766
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Tested-by: Volker Mische <volker.mische@gmail.com>