Org: latex, improve tangled file embedding

Fix implementation to work with latest Org, and make the description a
tad more ... descriptive.

config.org

@@ -7709,53 +7709,20 @@ access.
 #+end_src
 
 In the "universal preamble", we already embed the source =.org= file, but it would
-be nice to embed all the tangled files. This is fairly easy to accomplish using
-a cannibalised version of ~org-babel-tangle~ which just collects the file names of
-each block that is tangled.
-
-#+begin_src emacs-lisp
-(defun org-babel-tangle-files ()
-  "All files that may be tangled to.
-Uses a stripped-down version of `org-babel-tangle'"
-  (let (files)
-    (save-excursion
-      (mapc ;; map over all languages
-       (lambda (by-lang)
-         (let* ((lang (car by-lang))
-                (specs (cdr by-lang))
-                (ext (or (cdr (assoc lang org-babel-tangle-lang-exts)) lang)))
-           (mapc
-            (lambda (spec)
-              (let ((get-spec (lambda (name) (cdr (assoc name (nth 4 spec))))))
-                (let* ((tangle (funcall get-spec :tangle))
-                       (base-name (cond
-                                   ((string= "yes" tangle)
-                                    (file-name-sans-extension
-                                     (nth 1 spec)))
-                                   ((string= "no" tangle) nil)
-                                   ((> (length tangle) 0) tangle)))
-                       (file-name (when base-name
-                                    ;; decide if we want to add ext to base-name
-                                    (if (and ext (string= "yes" tangle))
-                                        (concat base-name "." ext) base-name))))
-                  (push file-name files))))
-            specs)))
-       (org-babel-tangle-collect-blocks)))
-    (delq nil (cl-delete-duplicates files :test #'string=))))
-#+end_src
-
-From here it is trivial to map each file to a form which embeds the file if it
-exists.
+be nice to embed all the tangled files. This is fairly easy to accomplish by
+mapping each tangled file to a form which embeds the file if it exists.
 #+begin_src emacs-lisp
 (defun org-latex-embed-tangled-files ()
   "Return a string that uses embedfile to embed all tangled files."
   (mapconcat
    (lambda (tangle-file)
-     (format "\\IfFileExists{%1$s}{\\embedfile[desc=A tangled file]{%1$s}}{}"
-             (->> tangle-file
-                  (replace-regexp-in-string "\\\\" "\\\\\\\\")
-                  (replace-regexp-in-string "~" "\\\\string~"))))
-   (org-babel-tangle-files)
+     (format "\\IfFileExists{%1$s}{\\embedfile[desc=Tangled %2$s file]{%1$s}}{}"
+             (->> (car tangle-file)
+               (replace-regexp-in-string "\\\\" "\\\\\\\\")
+               (replace-regexp-in-string "~" "\\\\string~"))
+             (cdr tangle-file)))
+   (mapcar (lambda (f-block) (cons (car f-block) (caadr f-block)))
+           (org-babel-tangle-collect-blocks)) ; all files being tangled to
    "\n"))
 #+end_src