Fortran: provide a module/variable which determines/contains platform module search paths
Some platforms (notably Fedora) place Fortran modules in a location that is not searched by default. CMake should either extract this from the compiler (though Fedora's
gfortran build seems oblivious) or provide a module which discovers it.
FWIW, Debian seems to install modules (for HDF5 at least) under
/usr/include/hdf5/$buildmode. It is unclear how installing multi-arch Fortran development packages works on Debian.