net/openldap26-server compile ppm module

From: Per olof Ljungmark <peo_at_nethead.se>
Date: Sun, 12 Nov 2023 15:54:37 UTC
I am asking for advice how to compile
contrib/slapd-modules/ppm
in net/openldap26-server

Some modules in contrib/ are already in the configure list but ppm is 
not. Maybe a simple change in the Makefile would do it?

I have cc'd the maintainer here for a humble request to include ppm in 
the standard Makefile.

Thanks!

/Per