[CBD-1191]: change privilege to memcached-gerrit.sh

Change-Id: I914bac8d8afa05dccad671bf0b4ec74edbb750f4
Reviewed-on: http://review.couchbase.org/34347
Reviewed-by: Eric Limare <eric.limare@couchbase.com>
Tested-by: Eric Limare <eric.limare@couchbase.com>
Reviewed-by: Philip Labee <philip@couchbase.com>