Some additional information from Jeff Mincy:

Date: Mon, 12 Nov 2012 09:53:42 -0500

 
The problem is that  c-emacs-features has 'add-hook-local in cc-defs.el

This code returns t in 21.4.22 which causes 'add-hook-local to be
added to c-emacs-features

        (let ((buf1 (generate-new-buffer " test1"))
	      (buf2 (generate-new-buffer " test2"))
	      changed)
	  
	  (save-excursion		; Needed for XEmacs's byte compiler
	    (set-buffer buf1)
	    (add-hook 'after-change-functions
		      (lambda (beg end old-len) (setq changed t))
		      nil
		      t)
	    (set-buffer buf2)
	    (insert ?c)
	    (set-buffer buf1)
	    (remove-hook 'after-change-functions
			 (lambda (beg end old-len) (setq changed t))
			 t)
	    (kill-buffer buf1)
	    (kill-buffer buf2)
	    (not changed)))

In 21.4.22 the add-hook sets the global hook.  There seems to be
something preventing the after-change-functions hook from becoming
active immediately after it is added.