Ticket #47808 - If be_txn plugin fails in ldbm_back_add, adding entry is double freed.

Bug description: Backend add ldbm_back_add frees the entry to be added,
if the add fails in the be_txn plugins.  But the frontend releases the
entry when an error is returned from the backend.

Fix desxription: When the entry is freed in the backend, set NULL to
the pblock SLAPI_ADD_ENTRY to tell the frontend not to free the entry.

https://fedorahosted.org/389/ticket/47808

Reviewed by mreynolds@redhat.com (Thank you, Mark!!)
(cherry picked from commit d50f99476386b6c464884d2d16a688ecafc7fafc)
(cherry picked from commit 1f3510ad05e07667e0ec16c82baa2d4909675889)
Ticket 47813 - managed entry plugin fails to update member
 pointer on modrdn operation

Bug Description:  A modrdn on an existing managed entry failed to update
                  the entry pointer becuase part of the update is to add
                  the managed entry objectclass - which already exists
                  in the managed entry.  This caused the new pointer value
                  to not be added to the managed entry.

Fix Description:  During a modrdn operation perform the objectclass addition
                  in a separate operation, as we don't know if the entry
                  already has the objectclass or not.

https://fedorahosted.org/389/ticket/47813

TET: passed
Jenkins: passed

Reviewed by: rmeggins(Thanks!)

(cherry picked from commit 0fe78df27bea0ed29f5f74266bc530832e0d8906)
Ticket 47813 - remove "goto bail" from previous commit

https://fedorahosted.org/389/ticket/47813
(cherry picked from commit 4cdd7fd6ad41ff5d92dfd452b6a7bef25462b643)