org-src: Fix "not in a sub-edit buffer" error on save

* lisp/org-src.el (org-src-mode): Fix "not in a sub-edit buffer" error
  on save.

Reported-by: Detlef Steuer <detlef.steuer@gmx.de>
<http://permalink.gmane.org/gmane.emacs.orgmode/97349>

lisp/org-src.el

@@ -535,7 +535,7 @@ with \",*\", \",#+\", \",,*\" and \",,#+\"."
     map))
 
 (define-minor-mode org-src-mode
-  "Minor mode for language major mode buffers generated by org.
+  "Minor mode for language major mode buffers generated by Org.
 \\<org-mode-map>
 This minor mode is turned on in two situations:
   - when editing a source code snippet with \\[org-edit-special]
@@ -544,6 +544,7 @@ This minor mode is turned on in two situations:
 \\{org-src-mode-map}
 
 See also `org-src-mode-hook'."
+  nil " OrgSrc" nil
   (when org-edit-src-persistent-message
     (org-set-local
      'header-line-format