Use define-minor-mode in more cases.

Use define-minor-mode in more cases.
* term/tvi970.el (tvi970-set-keypad-mode):
* simple.el (auto-fill-mode, overwrite-mode, binary-overwrite-mode)
(normal-erase-is-backspace-mode):
* scroll-bar.el (scroll-bar-mode): Use it and define-minor-mode.
(set-scroll-bar-mode-1): (Re)move to its sole caller.
(get-scroll-bar-mode): New function.
* emacs-lisp/cl-macs.el (eq): Handle a non-variable first arg.