busybox

The Software Freedom Law Center wants us to add a copyright notice to the
generated binaries, to make copyright enforcement easier.  Our liason with
them (Bradley Kuhn) suggested the following text:

> Copyright (C) YEAR-2006  Erik Andersen, Rob Landley, and others.
> Licensed under GPLv2.  See source distribution for full notice.

And the busybox help message seems the least offensive place to put it.  (At
some point in the future, I need to strip 128 bytes from the binary to feel
good about this, though. :)

Minor header file cleanup while I was there, since libbb.h already #includes
most of that stuff...