differently with different OSDs
Switch back to building for all OSDs in common directory
Move more OSD-specific stuff into OSD scripts
It still isn't completely safe to be building all OSD into same directory
Common OSD "module" files, e.g. debuggers and renderers, build with
different options for each OSD. It works at the moment, but you will end
up with slightly different executables depending on the order you build
OSDs.
