(ITS#7570) fix MDB_GET_MULTIPLE and MDB_NEXT_MULTIPLE behaviour

[claude.brisson@gmail.com]

Full_Name: Claude Brisson
Version: HEAD
OS: linux 64
URL: ftp://ftp.openldap.org/incoming/0001-fix-MDB_GET_MULTIPLE-and-MDB_NEXT_MULTIPLE.patch
Submission from: (NULL) (84.103.74.130)


In a db with MDB_DUPSORT flag, when there is only one DUP data for a key,
F_DUPDATA is not set for this key, and there is no sub-cursor.

In this case, the current behaviour of MDB_GET_MULTIPLE and MDB_NEXT_MULTIPLE is
broken because they make the assumption that there is always a sub-cursor for
DUP data, which is only true for keys with more than one DUP data.

This patch address this specific issue.

Notice: I, Claude Brisson, hereby place the following modifications to OpenLDAP
Software (and only these modifications) into the public domain. Hence, these
modifications may be freely used and/or redistributed for any purpose with or
without attribution and/or other notice.