Clean up scoping rule of predefined single-word vars.

Clean up scoping rule of predefined single-word vars.
* lisp/startup.el (argv, argi): Make lexically scoped.
* lisp/emacs-lisp/float-sup.el (pi): Use internal-make-var-non-special.
* lisp/emacs-lisp/cl-macs.el: Use lexical-binding.
Rename cl-bind-* to cl--bind-*.
* lisp/files.el: Don't require `cl' since it doesn't use it.
* lisp/emacs-lisp/pcase.el, lisp/emacs-lisp/macroexp.el: Add coding cookie.
* src/eval.c (Fmake_var_non_special): New primitive.
(syms_of_eval): Defsubr it.
* src/lread.c (syms_of_lread): Mark `values' as lexically scoped.