Remove spurious defvar

Thanks to Nicolas Goaziou for reporting this.

lisp/org.el

@@ -4382,14 +4382,6 @@ If yes, offer to stop it and to save the buffer with the changes."
   (add-hook 'org-mode-hook 'org-clock-load)
   (add-hook 'kill-emacs-hook 'org-clock-save))
 
-;; Define the variable already here, to make sure we have it.
-(defvar org-indent-mode nil
-  "Non-nil if Org-Indent mode is enabled.
-Use the command `org-indent-mode' to change this variable.")
-
-;; Autoload archiving code
-;; The stuff that is needed for cycling and tags has to be defined here.
-
 (defgroup org-archive nil
   "Options concerning archiving in Org-mode."
   :tag "Org Archive"