OpenLDAP 2.5.16

OpenLDAP 2.5.15

This is option #1

When configuring OpenLDAP using --with-tls=openssl with LibreSSL the
configure will fail to detect SSL_export_keyring_material_early() since
LibreSSL doesn't support this function yet. However OpenLDAP doesn't
actually use this function and only checks for it to ensure a modern
OpenSSL API is used. This can be easily solved by checking for an
equivalent modern OpenSSL function which both LibreSSL and OpenSSL both
support such as SSL_CTX_set_ciphersuites(). Doing this allows the build
and tests to succeed with modern LibreSSL versions. This was tested with
LibreSSL >= 3.6.

Bug: https://bugs.openldap.org/show_bug.cgi?id=10039