ob-lob: ensure 'cl is loaded during compilation so we can use flet

* lisp/ob-lob.el (require): Ensure 'cl is loaded during compilation so
  we can use flet.

lisp/ob-lob.el

@@ -23,6 +23,8 @@
 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
 
 ;;; Code:
+(eval-when-compile
+  (require 'cl))
 (require 'ob)
 (require 'ob-table)