net/openldap26-server compile ppm module

[Per olof Ljungmark]

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