Ticket 47577 - crash when removing entries from cache
Bug Description: when the dn of an entry in the cache was adjusted to the parent dn, for soenm time
teh dn was not defined, anothe thread accessing the dn of teh chached entry could crash
Fix Description: hold the cache mutex when modifyingthe dn of an entry in the cache
https://fedorahosted.org/389/ticket/47577
Reviewed by: rmeggins