@fgeorgatos: This is only a sanity check, it's by no means meant to be exhaustive.

Besides that: nothing really changed here, the mpi_mods stuff was factored out higher up, so checking for `include/mpi.mod` is still part of the sanity check for all MPI versions.
For v4.x however, we now also check for `mpi_base.mod`, `mpi_constants.mod`, and `mpi_sizeofs.mod` include files, which weren't there in older Intel MPI version (3.x).

So, that part is actually an enhancement for installing old Intel MPI versions (which I had to do a while ago).