Add opaque to upr close stream api

Change-Id: I21dec3bbe8bbe15d9829894b21ce8ad59e3ba0a0
Reviewed-on: http://review.couchbase.org/32350
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>