build: Don't install elisp files when Emacs is unavailable.

* emacs.am (dist_lisp_DATA, nodist_lisp_DATA): Wrap in 'if HAVE_EMACS'.

emacs.am

@@ -27,6 +27,8 @@ ELFILES =					\
   emacs/guix-utils.el				\
   emacs/guix.el
 
+if HAVE_EMACS
+
 dist_lisp_DATA =				\
   $(ELFILES)					\
   $(AUTOLOADS)
@@ -34,8 +36,6 @@ dist_lisp_DATA =				\
 nodist_lisp_DATA =				\
   emacs/guix-init.el
 
-if HAVE_EMACS
-
 $(AUTOLOADS): $(ELFILES)
 	$(EMACS) --batch --eval						\
 	  "(let ((backup-inhibited t)					\