Please review: [389 Project] #47808: If be_txn plugin fails in ldbm_back_add, adding entry is double freed.

[Noriko Hosoi]

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

https://fedorahosted.org/389/attachment/ticket/47808/0001-Ticket-47808-If...

  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.