slapo-accesslog: Preserve some attributes of deleted entries in auditDelete entries

HI!

When using slapo-accesslog in a meta-directory environment you might wanna query the accesslog database for quickly detecting deleted entries with (&(objectClass=auditDelete)(reqResult=0)(<time-interval-filter>) and act accordingly. Now when receiving this entry of object class auditDelete the entry referenced by 'reqDN' is already gone. But the primary key used for synchronization might be some attribute within the deleted entry and not being part of the DN.

So it would be helpful to preserve a set of configurable attributes of the deleted entry in those entries of object class 'auditDelete' in the accesslog database just like attribute 'reqOld' for modify and modifyDN requests (configurable with logold/logoldattr).

Ciao, Michael.