Replace recent fix for vc-auto-revert-mode autoload problem

* lisp/emacs-lisp/easy-mmode.el (define-globalized-minor-mode):
Wrap references to MODE-variable in bound-and-true-p.
* lisp/vc/vc-hooks.el (auto-revert-mode): Restore to compilation
declaration only.

lisp/emacs-lisp/easy-mmode.el

@@ -567,7 +567,7 @@ Disable the mode if ARG is a negative number.\n\n"
 	 (dolist (buf (buffer-list))
 	   (with-current-buffer buf
              (if ,global-mode (funcall ,turn-on-function)
-               (when ,MODE-variable (,mode -1)))))
+               (when (bound-and-true-p ,MODE-variable) (,mode -1)))))
          ,@body)
 
        ,(when predicate
@@ -629,7 +629,7 @@ list."
                  ;; If one of them declines to turn the minor mode on,
                  ;; that should not mean the others can't.
                  (,MODE-suppress-set-explicitly t))
-             (if ,MODE-variable
+             (if (bound-and-true-p ,MODE-variable)
                  (progn
                    (,mode -1)
                    (funcall ,turn-on-function))