build and install saslauthd-port from cbauth package

Change-Id: I36e859315eda279220100a04dea3e4d77959af94
Reviewed-on: http://review.couchbase.org/44210
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>