fix HierarchicalMNS for cgoolf and goolfc toolchains + add iompi definition

This enables making HierarchicalMNS compatible with the `goolfc`, `cgoolf` and `iomkl` toolchain (see also https://github.com/hpcugent/easybuild-easyconfigs/pull/1099 w.r.t. `iomkl`)
I don't think that can work... It might for only the name, but we need to determine the version part too, which can't be easily pushed into a dict imho...