Fix C-M-x in lexbind mode. Misc tweaks.

Fix C-M-x in lexbind mode.  Misc tweaks.
* lisp/startup.el: Convert to lexical-binding.  Mark unused arguments.
(command-line-1): Get rid of the "cl1-" prefix now that we use lexical
scoping instead.
* lisp/emacs-lisp/float-sup.el (pi): Leave it lexically scoped.
* lisp/emacs-lisp/lisp-mode.el (eval-sexp-add-defvars): New fun.
(eval-last-sexp-1): Use eval-sexp-add-defvars.
* lisp/emacs-lisp/edebug.el (edebug-eval-defun): Use eval-sexp-add-defvars.
* lisp/emacs-lisp/cconv.el (cconv--analyse-function):
Fix `report-error/log-warning' mixup.