Turn of LaTeX preprocessing for table.el tables

* lisp/org-latex.el (org-export-latex-special-chars): Do nothing in
table.el tables.

Table.el does its own protection of special characters.

lisp/org-latex.el

@@ -1627,7 +1627,8 @@ See the `org-export-latex.el' code for a complete conversion table."
 	  (goto-char (point-min))
 	  (while (re-search-forward c nil t)
 	    ;; Put the point where to check for org-protected
-	    (unless (get-text-property (match-beginning 2) 'org-protected)
+	    (unless (or (get-text-property (match-beginning 2) 'org-protected)
+			(org-at-table.el-p))
 	      (cond ((member (match-string 2) '("\\$" "$"))
 		     (if (equal (match-string 2) "\\$")
 			 nil