nwchem-6.8 is broken

[jaimergp]

It was compiled against openmpi 3.0 (and unpinned!), but that version is no longer available in conda-forge (considered broken). Now, it would installed with openmpi 3.1, which fails with:

error while loading shared libraries: libmpi_usempi.so.40: cannot open shared object file: No such file or directory

I will update the recipe to pin it to 3.1 and also update it to nwchem-6.8.1. Building as I write.

Current build for version 6.8 will be labelled as broken.

[jaimergp]

I think I was doing some progress, but I didn't get it to work. I guess people will have to use their system's packages for now (available for Fedora/CentOS, Debian/Ubuntu and Arch Linux).

My last attempt is referenced in commit bd65ef7.