Treat mpi_family MPICH as MPICH 3.x instead of MPICH 1.x

Several easyblocks either don't handle the mpi_family MPICH at all or treat them as MPICH 1.x. This is addressed by this PR at least for some packages. Other easyblocks that may need modifications are:
 - aladin
 - esmf
 - imkl
 - nwchem
 - rmpi

However, I have never installed any of those, i.e., it would be good if someone else could help out.

Note that this PR is related to hpcugent/easybuild-framework#1073,  hpcugent/easybuild-framework#1101, and hpcugent/easybuild-easyconfigs#1217, although I believe that the changes proposed here are required in any case.