Missing Fortran interface files

It looks like there are Fortran source files that should have been transferred to the library from the ICON repository but were not. For example, src/shared/mo_util_sysinfo.f90 in the ICON repo is a Fortran interface to src/util_sysinfo.c in this repo. There might be more. We should check that and try to keep C implementations with their Fortran interfaces in one repo.

We discussed in today librarization meeting. In January there should be time to do so

Another example but in a different context is mentioned in #22.