Ricardo tested Emacs 25 with this package definition:
<http://paste.lisp.org/display/320941> and noticed that it doesn't find
Emacs packages in ~/.guix-profile.

This happens because "site-start.el" in the inherited package is placed
"/share/emacs/24.5/site-lisp" directory (the version part is wrong).  To
avod this, we can put "site-start.el" into a non-versioned site-lisp
directory.  The patch is attached.