Support for PDB debug information generation

It would be great if GHC support PDB files for debugging. This will help in Windows debugging and it will gain more stronger positions on Windows platform. There are great Windows tools for profiling and debugging that are sitting on PDB files.

Here I found format description. I'm not sure if it is similar to DWARF so it could be easily generated from existing DWARF implementation. https://github.com/Microsoft/microsoft-pdb