New user option 'Buffer-menu-human-readable-sizes'

* lisp/buff-menu.el (Buffer-menu-human-readable-sizes): New user
option.
(list-buffers--refresh): Use it.
* etc/NEWS: Announce the new user option.  (Bug#75825)

etc/NEWS

@@ -402,6 +402,12 @@ set to 'title'.
 *** New user option 'ibuffer-human-readable-size'.
 When non-nil, buffer sizes are shown in human readable format.
 
+---
+** Buffer Menu
+*** New user option 'Buffer-menu-human-readable-sizes'.
+When non-nil, buffer sizes are shown in human readable format.  The
+default is nil, which retains the old format.
+
 ** Smerge
 *** New command 'smerge-extend' extends a conflict over surrounding lines.
 

lisp/buff-menu.el

@@ -135,6 +135,14 @@ If this is nil, group names are unsorted."
   :group 'Buffer-menu
   :version "30.1")
 
+(defcustom Buffer-menu-human-readable-sizes nil
+  "If non-nil, show buffer sizes in human-readable format.
+That means to use `file-size-human-readable' (which see) to format the
+buffer sizes in the buffer size column."
+  :type 'boolean
+  :group 'Buffer-menu
+  :version "31.1")
+
 (defvar-local Buffer-menu-files-only nil
   "Non-nil if the current Buffer Menu lists only file buffers.
 This is set by the prefix argument to `buffer-menu' and related
@@ -831,7 +839,10 @@ See more at `Buffer-menu-filter-predicate'."
 				(if buffer-read-only "%" " ")
 				(if (buffer-modified-p) "*" " ")
 				(Buffer-menu--pretty-name name)
-				(number-to-string (buffer-size))
+				(funcall (if Buffer-menu-human-readable-sizes
+                                             #'file-size-human-readable
+                                           #'number-to-string)
+                                         (buffer-size))
 				(concat (format-mode-line mode-name
                                                           nil nil buffer)
 					(if mode-line-process