ox-latex: Improve handling of footnotes within verse blocks

* lisp/ox-latex.el (org-latex-footnote-reference): Use the footmark +
footnotetext combination for footnotes in verse environments.
(org-latex-verse-block): Use `org-latex--delayed-footnotes-definitions'.

Reported-by: Juan Manuel Macías <maciaschain@posteo.net>
<http://lists.gnu.org/r/emacs-orgmode/2020-12/msg00006.html>

lisp/ox-latex.el

@@ -1888,10 +1888,11 @@ CONTENTS is nil.  INFO is a plist holding contextual information."
 		(org-export-get-footnote-definition footnote-reference info)
 		info t)))
       ;; Use \footnotemark if reference is within another footnote
-      ;; reference, footnote definition, table cell or item's tag.
+      ;; reference, footnote definition, table cell, verse block, or
+      ;; item's tag.
       ((or (org-element-lineage footnote-reference
 				'(footnote-reference footnote-definition
-						     table-cell))
+						     table-cell verse-block))
 	   (eq 'item (org-element-type
 		      (org-export-get-parent-element footnote-reference))))
        "\\footnotemark")
@@ -1903,7 +1904,8 @@ CONTENTS is nil.  INFO is a plist holding contextual information."
 		  ;; Only insert a \label if there exist another
 		  ;; reference to def.
 		  (cond ((not label) "")
-			((org-element-map (plist-get info :parse-tree) 'footnote-reference
+			((org-element-map (plist-get info :parse-tree)
+			     'footnote-reference
 			   (lambda (f)
 			     (and (not (eq f footnote-reference))
 				  (equal (org-element-property :label f) label)
@@ -3504,21 +3506,25 @@ channel."
   "Transcode a VERSE-BLOCK element from Org to LaTeX.
 CONTENTS is verse block contents.  INFO is a plist holding
 contextual information."
-  (org-latex--wrap-label
-   verse-block
-   ;; In a verse environment, add a line break to each newline
-   ;; character and change each white space at beginning of a line
-   ;; into a space of 1 em.  Also change each blank line with
-   ;; a vertical space of 1 em.
-   (format "\\begin{verse}\n%s\\end{verse}"
-	   (replace-regexp-in-string
-	    "^[ \t]+" (lambda (m) (format "\\hspace*{%dem}" (length m)))
+  (concat
+   (org-latex--wrap-label
+    verse-block
+    ;; In a verse environment, add a line break to each newline
+    ;; character and change each white space at beginning of a line
+    ;; into a space of 1 em.  Also change each blank line with
+    ;; a vertical space of 1 em.
+    (format "\\begin{verse}\n%s\\end{verse}"
 	    (replace-regexp-in-string
-	     "^[ \t]*\\\\\\\\$" "\\vspace*{1em}"
+	     "^[ \t]+" (lambda (m) (format "\\hspace*{%dem}" (length m)))
 	     (replace-regexp-in-string
-	      "\\([ \t]*\\\\\\\\\\)?[ \t]*\n" "\\\\\n"
-	      contents nil t) nil t) nil t))
-   info))
+	      "^[ \t]*\\\\\\\\$" "\\vspace*{1em}"
+	      (replace-regexp-in-string
+	       "\\([ \t]*\\\\\\\\\\)?[ \t]*\n" "\\\\\n"
+	       contents nil t) nil t) nil t))
+    info)
+   ;; Insert footnote definitions, if any, after the environment, so
+   ;; the special formatting above is not applied to them.
+   (org-latex--delayed-footnotes-definitions verse-block info)))