Ticket #47780 - Some VLV search request causes memory leaks

Fix description:
. Modified idl_free interface as follows so that passed idl is cleared
  with NULL once the IDList is successfully freed.
    -idl_free(IDList *idl)
    +idl_free(IDList **idl)
  This change is used to clean up search candidates when ldbm_back_
  search_cleanup (ldbm_search.c) is called as an error return.  The
  cleanup function frees the search candidates when it's not NULL and
  it's not assigned to sr_candidates field in the search result. This
  fixes a memory leak when VLV/Sort op fails.
. ldbm_back_search_cleanup (ldbm_search.c) calls slapi_send_ldap_result
  if an ldap error is passed to the function.  The logic used to be
  "if (ldap_result>=LDAP_SUCCESS)", which is based upon that mozldap
  return codes are all positive.  Supporting openldap library, there
  is a chance to get a negative return code (e.g. LDAP_PARAM_ERROR ==
  -9).  This patch supports the negative return codes, as well.
. In ldbm_back_search (ldbm_search.c) vlv_filter_candidates could
  ruturn errors such as and LDAP_TIMELIMIT_EXCEEDED, LDAP_ADMINLIMIT_
  EXCEEDED.  The search results are supposed to be returned to the
  client with the error code if the control is not critical.  The code
  is added.
. The VLV operation stores the result in vlv_response_control.result
  in ldbm_back_search (ldbm_search.c), which occurs at 3 places, vlv_
  filter_candidates, sort_candidates and vlv_trim_candidates_txn.
  The return code from the latter calls used to override the former
  return code.  This patch fixes it to respect the former return code.

https://fedorahosted.org/389/ticket/47780

Reviewed by rmeggins@redhat.com (Thank you, Rich!!)

(cherry picked from commit 1118cc9b61a60c704250080d6af8785e4f8d28af)
(cherry picked from commit e9f86dab95fd600b414cf1c4cf6f7c733348b758)
Ticket #47804 - db2bak.pl error with changelogdb

Bug description: Backup utility db2bak[.pl] copies not just backend
db files but also changelog db files, which is not associated with
the backend instance, but the backend code blindly expected it.

Fix description: If the copying directory is a changelog db dir,
skip retrieving the backend instance info and just copy the files
underneath

https://fedorahosted.org/389/ticket/47804

Reviewed by rmeggins@redhat.com (Thank you, Rich!!)
(cherry picked from commit a6c24c5bf1216e6dceaf014a25ce60a5a714635c)