One can rig things up so that configuration systems walk the path and try the locations on it, so that they’ll find things whether they’re in /usr/local or /opt/local or whatever. A good guess is always that if you have a path element named /FOO/bin, then you should check /FOO/lib, /FOO/include, etc.
It’s just too complicated ATM, I still couldn’t install the mpi package. Trying to reinstall openmpi-devel-default maybe it was port that messed up. Takes too many tries.
Ok this was the reason, if you get weird errors about conf-* packages not installing then you probably have to reinstall the macports packages… I removed all variants of openmpi and then reinstalled, that did work…