bug#38533: emacs-auctex breaks url package

[Diego Nicola Barbato]

Hi Guix,

AUCTeX breaks Emacs' bult-in url package.  This bug appears to have been
introduced with commit 3ffdd00 and can be reproduced as follows:

1) Install ‘emacs’ and ‘emacs-auctex’.
2) Start Emacs and do M-: (require 'url), which will produce the
   following backtrace:
--8<---------------cut here---------------start------------->8---
Debugger entered--Lisp error: (void-function TeX-add-style-hook)
  (TeX-add-style-hook "url" #f(compiled-function () #<bytecode 0x48bbdd>) 
LaTeX-dialect)
  require(url)
  eval((require (quote url)) nil)
  eval-expression((require (quote url)) nil nil 127)
  funcall-interactively(eval-expression (require (quote url)) nil nil 127)
  call-interactively(eval-expression nil nil)
  command-execute(eval-expression)
--8<---------------cut here---------------end--------------->8---

It looks like Emacs tries to load the file
$GUIX_PROFILE/share/emacs/site-lisp/style/url.elc, which is provided by
‘emacs-auctex’, instead of
$GUIX_PROFILE/share/emacs/26.3/lisp/url/url.elc, which is provided by
Emacs itself.

Regards,

Diego