MB-100: new toybuild for MB8938

Change-Id: I1ee9023924a92b55bf80c1626f7e72d048227fa0
Reviewed-on: http://review.couchbase.org/28637
Reviewed-by: Junyi Xie <junyi.couchbase@gmail.com>
Tested-by: Junyi Xie <junyi.couchbase@gmail.com>