Hi,
you may want to have a look at Followup 1 for ITS#8205: I added a manual page for pbkdf2 and adapted it's Makefile to install it too.
The commit can be found on my github repo: https://github.com/marschap/openldap/commit/f63202e8aa68e3391f52d2481f649ca2...
BTW: I successfully tested your nettle patch with by Debian-based server. Thank you!
Best Peter