X11 build system

[brook%biology.nmsu.edu@localhost (Brook Milligan)]

Would someone mind explaining how the X11 build system works to pull
parts from /usr/xsrc/external/mit?

I would like to add import dmx and add support for it to our build
process, but there are a bunch of magic make variables getting used
and I'm afraid I don't see where they are set.  As a result, I cannot
modify what is there to include the new code.

Any help and guidance is greatly appreciated.  Thanks.

Cheers,
Brook