r5585: LDB interfaces change:

r5585: LDB interfaces change:

changes:
- ldb_wrap disappears from code and become a private structure of db_wrap.c
  thanks to our move to talloc in ldb code, we do not need to expose it anymore

- removal of ldb_close() function form the code
  thanks to our move to talloc in ldb code, we do not need it anymore
  use talloc_free() to close and free an ldb database

- some minor updates to ldb modules code to cope with the change and fix some
  bugs I found out during the process
(This used to be commit d58be9e74b786a11a57e89df36081d55730dfe0a)