Cleanup hwloc integration logic in cmake

[igchor]

Logic for static linking with hwloc is different on windows and linux. We should try to unify it, perhaps by creating our own CMakeLists.txt based on https://github.com/open-mpi/hwloc/tree/master/contrib/windows-cmake that would work for both linux and windows (and perhaps MacOS on which we do not support static linking right now).