Log Message:
* Use a right PLIST file for XEmacs.
* Don't depend on xemacs-packages.

While files of xemacs-packages are installed into
  	${PREFIX}/lib/xemacs/xemacs-packages,
individual Emacs lisp packages use
  	${PREFIX}/lib/xemacs/site-packages,
so these are never overwritten.

Let's think that these two parts are separate.  Individual Emacs lisp
packages depend on another individual ones, never need to depend on
xemacs-packages.  This should make things simpler.