Misc fixes, and use lexical-binding in more files.

* lisp/subr.el (letrec): New macro.
(with-wrapper-hook): Move from lisp/simple.el and don't use CL.
* simple.el (with-wrapper-hook): Move with-wrapper-hook to subr.el.
* lisp/help-fns.el (help-function-arglist): Handle subroutines as well.
(describe-variable): Use special-variable-p to filter completions.
* lisp/emacs-lisp/macroexp.el (macroexpand-all-1): Don't expand `declare'
in defmacros.
* lisp/emacs-lisp/cconv.el (cconv-convert, cconv-analyse-form):
Handle `declare'.
* lisp/emacs-lisp/cl.el (pushnew): Silence unfixable warning.
* lisp/emacs-lisp/cl-macs.el (defstruct, define-compiler-macro):
Mark unused arg as unused.
* lisp/emacs-lisp/byte-opt.el (byte-optimize-lapcode): Use memq.
* lisp/emacs-lisp/autoload.el (make-autoload): Don't assume the macro's
first sexp is a list.
(autoload-generate-file-autoloads): Improve error message.
* lisp/emacs-lisp/advice.el (ad-arglist): Use help-function-arglist
to understand the new byte-code arg format.
* lisp/vc/smerge-mode.el:
* lisp/vc/log-view.el:
* lisp/vc/log-edit.el:
* lisp/vc/cvs-status.el:
* lisp/uniquify.el:
* lisp/textmodes/css-mode.el:
* lisp/textmodes/bibtex-style.el:
* lisp/reveal.el:
* lisp/newcomment.el:
* lisp/emacs-lisp/smie.el:
* lisp/abbrev.el: Use lexical-binding.
* src/eval.c (Fprog1, Fprog2): Simplify and use XCDR/XCAR.
(Fdefvar): Remove redundant SYMBOLP check.
(Ffunctionp): Don't signal an error for undefined aliases.
* doc/lispref/variables.texi (Converting to Lexical Binding): New node.

lisp/emacs-lisp/macroexp.el

@@ -131,7 +131,16 @@ Assumes the caller has bound `macroexpand-all-environment'."
       (`(defmacro ,name . ,args-and-body)
        (push (cons name (cons 'lambda args-and-body))
              macroexpand-all-environment)
-       (macroexpand-all-forms form 3))
+       (let ((n 3))
+         ;; Don't macroexpand `declare' since it should really be "expanded"
+         ;; away when `defmacro' is expanded, but currently defmacro is not
+         ;; itself a macro.  So both `defmacro' and `declare' need to be
+         ;; handled directly in bytecomp.el.
+         ;; FIXME: Maybe a simpler solution is to (defalias 'declare 'quote).
+         (while (or (stringp (nth n form))
+                    (eq (car-safe (nth n form)) 'declare))
+           (setq n (1+ n)))
+         (macroexpand-all-forms form n)))
       (`(defun . ,_) (macroexpand-all-forms form 3))
       (`(,(or `defvar `defconst) . ,_) (macroexpand-all-forms form 2))
       (`(function ,(and f `(lambda . ,_)))