org-macs: macro `org-with-limited-levels' also sets `outline-regexp'

* lisp/org-macs.el (org-with-limited-levels): some functions, like
  `org-back-to-heading', being deeply based on outline-mode, still
  refer to `outline-regexp' instead of `org-outline-regexp'.

lisp/org-macs.el

@@ -348,6 +348,7 @@ point nowhere."
 (defmacro org-with-limited-levels (&rest body)
   "Execute BODY with limited number of outline levels."
   `(let* ((org-outline-regexp (org-get-limited-outline-regexp))
+	  (outline-regexp org-outline-regexp)
 	  (org-outline-regexp-at-bol (concat "^" org-outline-regexp)))
      ,@body))