The only place this is needed is when determining the directory name
that the tar file will be extracted to. This can be done by examining
the .tar file name without needing to know the version itself.
These modules encapsulate individual pieces of functionality and make
the code far more maintainable. This is a pretty big refactoring but
overall a big win.
We need to distinguish between tools we compile to use as part of the
build process, and things we build for the eventual target. Install
these into separate install directories; for now, pkg-config is the
only one of these.
