adding warning to obsolete unicode branch

[Miles Bader]

As a large number of people used the emacs-unicode-2 branch
out of CVS, I think it might be a good idea to add a warning
to the configure script and Makefiles in the branch, so that
if they update from that branch and build emacs, they'll get
a big fat message telling them they should probably use the
trunk instead.

E.g.

********************************************************************
**                                                                **
**  The Emacs "emacs-unicode-2" branch has been merged into       **
**  the CVS trunk, and is now obsolete.  You should probably      **
**  use the CVS trunk instead.                                    **
**                                                                **
**  To switch a CVS checkout to the trunk, use the command:       **
**                                                                **
**     cvs update -A                                              **
**                                                                **
********************************************************************

The configure script is easy, though I'm not exactly sure
which make targets such a thing should be added to...

Any opinions?

Thanks,

-Miles

-- 
`To alcohol!  The cause of, and solution to,
 all of life's problems' --Homer J. Simpson