org-latex: ensure footnote contents cannot end a list

* lisp/org-latex.el (org-export-latex-preprocess): add
  `original-indentation' property to footnotes so they cannot possibly
  end a list by being less indented than the item they belong to.

lisp/org-latex.el

@@ -2443,6 +2443,8 @@ The conversion is made depending of STRING-BEFORE and STRING-AFTER."
 		 (add-text-properties (1- (length footnote-rpl))
 				      (length footnote-rpl)
 				      '(org-protected t) footnote-rpl)
+		 (put-text-property 0 (length footnote-rpl)
+				    'original-indentation 1000 footnote-rpl)
 		 (if (org-on-heading-p)
 		     (setq footnote-rpl
 			   (concat (org-export-latex-protect-string "\\protect")