MB-7468: point to updated portsigar

So that we can gather page fault stats

Change-Id: I0e950eb6d611d60ea978dab8911f3b34046e823b
Reviewed-on: http://review.couchbase.org/25068
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>