Use lexical-binding for all of CL, and clean up its namespace.

* lisp/emacs-lisp/cl-lib.el: Use lexical-binding.
(cl-map-extents, cl-maclisp-member): Remove.
(cl--set-elt, cl--set-nthcdr, cl--set-buffer-substring)
(cl--set-substring, cl--block-wrapper, cl--block-throw)
(cl--compiling-file, cl--mapcar-many, cl--do-subst): Use "cl--" prefix.
* lisp/emacs-lisp/cl-extra.el: Use lexical-binding.
(cl--mapcar-many, cl--map-keymap-recursively, cl--map-intervals)
(cl--map-overlays, cl--set-frame-visible-p, cl--progv-save)
(cl--progv-before, cl--progv-after, cl--finite-do, cl--set-getf)
(cl--do-remf, cl--do-prettyprint): Use "cl--" prefix.
* lisp/emacs-lisp/cl-seq.el: Use lexical-binding.
(cl--parsing-keywords, cl--check-key, cl--check-test-nokey)
(cl--check-test, cl--check-match): Use "cl--" prefix and backquotes.
(cl--alist, cl--sublis-rec, cl--nsublis-rec, cl--tree-equal-rec):
* lisp/emacs-lisp/cl-macs.el (cl--lambda-list-keywords): Use "cl--" prefix.
* lisp/edmacro.el (edmacro-mismatch): Simplify to remove dependence on
CL's internals.

lisp/emacs-lisp/bytecomp.el

@@ -1399,18 +1399,18 @@ extra args."
 	     ;; These aren't all aliases of subrs, so not trivial to
 	     ;; avoid hardwiring the list.
 	     (not (memq func
-			'(cl-block-wrapper cl-block-throw
+			'(cl--block-wrapper cl--block-throw
 			  multiple-value-call nth-value
 			  copy-seq first second rest endp cl-member
 			  ;; These are included in generated code
 			  ;; that can't be called except at compile time
 			  ;; or unless cl is loaded anyway.
-			  cl-defsubst-expand cl-struct-setf-expander
+			  cl--defsubst-expand cl-struct-setf-expander
 			  ;; These would sometimes be warned about
 			  ;; but such warnings are never useful,
 			  ;; so don't warn about them.
 			  macroexpand cl-macroexpand-all
-			  cl-compiling-file))))
+			  cl--compiling-file))))
 	(byte-compile-warn "function `%s' from cl package called at runtime"
 			   func)))
   form)