Fix openldap install instructions
Fix openldap install instructions

The Makefile (on the mdb.master branch) of the openldap.git repo is
under `libraries/liblmdb`. I have tested that you can `make` and `make
install` from there, and I'm assuming that's what this section is trying
to do. Perhaps the upstream repo shuffled some code around?

armon/gomdb,armon/gomdb