[2.0.2] updated portsigar to have latest stats gathering feature

Change-Id: I4ffeb76460d555f82309598489151521a0a54b1e
Reviewed-on: http://review.couchbase.org/26458
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>