MB-8445 Include important portsigar fix to branch-2.1.0.xml.

Change-Id: I882470480b431ac2daed29f84794ca11d0e8a0eb
Reviewed-on: http://review.couchbase.org/26888
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>