Ticket 49386 - Memberof should be ignore MODRDN when the pre/post entry are identical
If a modrdn command renames an entry in itself it is inexpensive for the
core server but can be expensive for memberof.
member will update all entries referring (memberof value) the target entry.
The updates will delete and add back the target entry DN.
In the early step of memberof modrdn callback, checks if pre_sdn and post_sdn
If they are it skips the update
Reviewed by: Mark Reynolds
Platforms tested: F23
Flag Day: no
Doc impact: no