Stop updating all the active records with UpdateMembershipRecord.php.txt

The UpdateMembershipRecord.php.txt runs the membership status update on all records that are not cancelled, expired, pending or overridden (essentially all active memberships plus a couple others) even if the status doesn't change. This patch only runs the update if the status changes, this will reduce the workload and stops updates being added the the civicrm_membership_log table when there has been no change in the record.