edir 873 to 88 upgrade removes customer optional attributes from CRLDistributionPoint

Servers no longer synchronize correctly after 873 to 88 upgrade.
Specifically, cRLDistributionPoint objects can't synchronize from an 873 to an 88 server.
A custom attribute has been added to the CRLDistributionPoint objectclass as an optional.

The 873 to 88 upgrade removed the custom attribute.  In order to get synchronization working again, manually add the missing custom attribute back to the cRLDistributionPoint objectclass.  Do NOT run dsrepair until the missing schema is present in the tree again, or the affected attribute data will be stripped from those objects that are of the cRLDistributionPoint class.