There is an updated pull request by klarasm against master on the void-packages repository

https://github.com/klarasm/void-packages openldap-2.6
https://github.com/void-linux/void-packages/pull/41948

openldap: update to 2.6.6
The 2.4 branch is not maintained anymore and I don't know if there's much advantage to going to 2.5 instead of 2.6

Some shared libraries have changed name so this updates common/shlibs.

As this is a major update the ldap database should be backed up and recreated as per https://www.openldap.org/doc/admin26/maintenance.html

#### Testing the changes
- I tested the changes in this PR: **YES** (mainly openldap, mit-krb5 and cyrus-sasl)
- I haven't tested the revbumped packages that much, other than building with their test suite

I have upgraded my ldap setup to this version. It's not very complicated so may not be great for coverage.
Basically:
- two nodes, with normal syncrepl and gssapi/kerberos for authentication
- the ldap directory is used as database backend for my kerberos setup
- I have a few machines setup with kerberos for authentication and ldap as id provider (some with sssd and some with nslcd)

This PR should not be merged before:
- [x] log4cxx-1.0.0 #42632
- [x] mit-krb5 1.20.1 #42633
- [x] python3-ldap-3.4.3 #42634
- [x] apr-util-1.6.3 #42636 (change in libtool resulted in cross-compilation failure)
- [x] virtuoso-7.2.9 #42666 (probably not critical, tests are already failing on master branch)
- [x] apache-2.4.56 #43108 (same failure as in apr-util)

[ci skip] again.

#### Local build testing
(updated 2023-08-23)

##### I built this PR locally for my native architecture, (x86_64-glibc):
- Build failures:
  - alpine (already failing on master branch)
- Test suite errors:
  - anjuta  (already failing on master branch)

##### I built this PR locally for my native architecture, (x86_64-musl):
- Build failures:
  -  sssd (does not support musl)
  -  alpine (already failing on master branch)
- Test suite errors:
  - anjuta (already failing on master branch)
  - audit (already failing on master branch)
  - dovecot (already failing on master branch)
  - nss-pam-ldapd (musl does not support nsswitch)

##### Crossbuilds
- aarch64-musl, build failures:
  - alpine (already failing on master branch)
  - sssd (does not support musl)
  - packages not supporting cross-compilation:
    - FreeRADIUS
    - libreoffice
    - virtuoso
    - x2goclient
- armv7l, build failures:
  - alpine (already failing on master branch)
  - packages not supporting cross-compilation:
    - FreeRADIUS
    - libreoffice
    - virtuoso
    - x2goclient
- armv6l-musl, build-failures:
  - alpine (already failing on master branch)
  - sssd (does not support musl)
  - packages not supporting cross-compilation:
    - FreeRADIUS
    - libreoffice
    - virtuoso
    - x2goclient
<!--
(old builds from 2023-07-13)
- I built this PR locally for my native architecture, (x86_64-glibc). All packages build.  Test suite errors:
  - anjuta  (already failing on master branch)
- I built this PR locally for my native architecture, (x86_64-musl). Except sssd (which does not support musl), all packages build. Test suite errors:
  - anjuta (already failing on master branch)
  - audit (already failing on master branch)
  - dovecot (already failing on master branch)
  - evolution-data-server (already failing on master branch)
  - nss-pam-ldapd (already failing on master, expected as musl does not support nsswitch)

- I built this PR locally for these architectures:
  - aarch64-musl (x2go-client, virtuoso, libreoffice and FreeRADIUS fail due to cross-compilation, sssd does not support musl, all other complete)
  - armv6l-musl (x2go-client, virtuoso, libreoffice and FreeRADIUS fail due to cross-compilation, sssd does not support musl, all other complete)
  - armv7l (x2go-client, virtuoso, libreoffice and FreeRADIUS fail due to cross-compilation, all other complete)
-->

A patch file from https://github.com/void-linux/void-packages/pull/41948.patch is attached