ox-texinfo.el: Fix escaping special chars in raw-path

* lisp/ox-texinfo.el (org-texinfo-link): Escape @, { and }
characters in the link path.

lisp/ox-texinfo.el

@@ -1046,7 +1046,10 @@ DESC is the description part of the link, or the empty string.
 INFO is a plist holding contextual information.  See
 `org-export-data'."
   (let* ((type (org-element-property :type link))
-	 (raw-path (org-element-property :path link))
+	 (raw-path
+	  (replace-regexp-in-string
+	   "[@{}]" "@\\&"
+	   (org-element-property :path link)))
 	 ;; Ensure DESC really exists, or set it to nil.
 	 (desc (and (not (string= desc "")) desc))
 	 (path (cond