The patches themselves remove support of old libdb (< 4.7).
However there is still question about code in ldap/servers/slapd/back-ldbm/upgrade.c
I haven't touched it because I have no idea which on-disk libdb formats
we can assume that users have. Can we, for example, assume that all
existing DS installations which will upgrade to current master branch
have at least libdb 4 on-disk format and newer? If yes, the upgrade.c code
can be cleaned as well.