This directory is much like ../media in the sense that it contains
drivers for various third party libraries, but is system-oriented
rather than media-oriented (e.g. if support for different kind of thread
libraries was needed, this would belong to this directory).

Make sure you read the comments in ../media/README, because this
directory is organized similary.

The ony group of system-facility handled here for now is

 - M : main  (some libraries need special `main()' arrangements)
