Add `declare' for `defun'. Align `defmacro's with it.

Add `declare' for `defun'.  Align `defmacro's with it.
* lisp/emacs-lisp/easy-mmode.el (define-minor-mode)
(define-globalized-minor-mode): Don't autoload the var definitions.
* lisp/emacs-lisp/byte-run.el: Use lexical-binding.
(defun-declarations-alist, macro-declarations-alist): New vars.
(defmacro, defun): Use them.
(make-obsolete, define-obsolete-function-alias)
(make-obsolete-variable, define-obsolete-variable-alias):
Use `declare'.
(macro-declaration-function): Mark obsolete.
* lisp/emacs-lisp/autoload.el: Use lexical-binding.
(make-autoload): Add `expansion' arg.  Rely more on macro expansion.