Export back-ends: Fix some compilation errors

* lisp/ox-beamer.el (require): Require cl when compiling.
* lisp/ox-icalendar.el (require): Require cl when compiling.
* lisp/ox-jsinfo.el (require): Require cl when compiling.
* lisp/ox-md.el (require): Require cl when compiling.

lisp/ox-beamer.el

@@ -108,6 +108,7 @@
 
 ;;; Code:
 
+(eval-when-compile (require 'cl))
 (require 'ox-latex)
 
 

lisp/ox-icalendar.el

@@ -43,6 +43,7 @@
 
 ;;; Code:
 
+(eval-when-compile (require 'cl))
 (require 'ox-ascii)
 (declare-function org-bbdb-anniv-export-ical "org-bbdb" nil)
 

lisp/ox-jsinfo.el

@@ -35,10 +35,12 @@
 
 ;;; Code:
 
+(eval-when-compile (require 'cl))
 (require 'ox-html)
 
 (add-to-list 'org-export-filter-options-functions 'org-infojs-install-script)
 
+
 (defgroup org-export-infojs nil
   "Options specific for using org-info.js in HTML export."
   :tag "Org Export HTML INFOJS"

lisp/ox-md.el

@@ -29,6 +29,7 @@
 
 ;;; Code:
 
+(eval-when-compile (require 'cl))
 (require 'ox-html)