Quieten cl-lib related compiler warnings

* lisp/completion.el (cl-set-difference):
* lisp/files.el (map-merge-with, map-merge):
* lisp/emacs-lisp/radix-tree.el (map-apply): Declare.
* lisp/emacs-lisp/thunk.el: Load cl-lib at run-time, not
cl-macs at compile.
* lisp/gnus/gnus-group.el: Load cl-lib at run-time, not cl at compile.
* lisp/emacs-lisp/checkdoc.el, lisp/emacs-lisp/package.el
* lisp/gnus/gnus-sum.el, lisp/gnus/message.el, lisp/net/shr.el:
Load cl-lib at run-time.
* lisp/gnus/mml-sec.el (mml-signencrypt-style)
(mml-secure-cust-record-keys): Replace cl with cl-lib,
and load it at run-time.
* lisp/cedet/ede/linux.el, lisp/vc/vc-hg.el: Reorder requires.

lisp/emacs-lisp/checkdoc.el

@@ -171,7 +171,7 @@
 (defvar checkdoc-version "0.6.1"
   "Release version of checkdoc you are currently running.")
 
-(eval-when-compile (require 'cl-lib))
+(require 'cl-lib)
 (require 'help-mode) ;; for help-xref-info-regexp
 (require 'thingatpt) ;; for handy thing-at-point-looking-at
 

lisp/emacs-lisp/package.el

@@ -143,8 +143,8 @@
 
 ;;; Code:
 
+(require 'cl-lib)
 (eval-when-compile (require 'subr-x))
-(eval-when-compile (require 'cl-lib))
 (eval-when-compile (require 'epg))      ;For setf accessors.
 (require 'seq)
 

lisp/emacs-lisp/radix-tree.el

@@ -235,6 +235,8 @@ PREFIX is only used internally."
     (radix-tree-iter-mappings tree (lambda (_k _v) (setq i (1+ i))))
     i))
 
+(declare-function map-apply "map" (function map))
+
 (defun radix-tree-from-map (map)
   ;; Aka (cl-defmethod map-into (map (type (eql radix-tree)))) ...)
   (require 'map)

lisp/emacs-lisp/thunk.el

@@ -48,7 +48,7 @@
 
 ;;; Code:
 
-(eval-when-compile (require 'cl-macs))
+(require 'cl-lib)
 
 (defmacro thunk-delay (&rest body)
   "Delay the evaluation of BODY."