recentf.el: Add verbosity option

* lisp/recentf.el (recentf-show-messages): New defcustom to
control verbosity.
(recentf-save-list): Use that to control verbosity.  (Bug#67946)

etc/NEWS

@@ -531,6 +531,13 @@ This user option controls the width of the type column on the bookmark
 menu 'bookmark-bmenu-list'.  The default value is 8 which is backwards
 compatible.
 
+** Recentf
+
+---
+*** New user option 'recentf-show-messages'.
+'recentf-save-list' can print a message when saving the recentf list.
+The new option, if set to nil, suppresses this message.
+
 ** Saveplace
 
 ---

lisp/recentf.el

@@ -321,6 +321,14 @@ If non-nil, `recentf-open-files' will show labels for keys that can be
 used as shortcuts to open the Nth file."
   :group 'recentf
   :type 'boolean)
+
+(defcustom recentf-show-messages t
+  "Whether to show verbose messages about low-level recentf actions.
+nil means to not show messages related to the recentf machinery.
+t means show messages that were printed by default on Emacs <= 31.1."
+  :group 'recentf
+  :type 'boolean
+  :version "31.1")
 
 ;;; Utilities
 ;;
@@ -1331,8 +1339,12 @@ Write data into the file specified by `recentf-save-file'."
         (insert "\n\n;; Local Variables:\n"
                 (format ";; coding: %s\n" recentf-save-file-coding-system)
                 ";; End:\n")
-        (write-region (point-min) (point-max)
-                      (expand-file-name recentf-save-file))
+        (write-region (point-min)
+                      (point-max)
+                      (expand-file-name recentf-save-file) nil
+                      (unless (or (called-interactively-p 'interactive)
+                                 recentf-show-messages)
+                        'quiet))
         (when recentf-save-file-modes
           (set-file-modes recentf-save-file recentf-save-file-modes))
         nil)