Bind Scroll_Lock to scroll-lock-mode globally

* lisp/bindings.el (global-map): Bind Scroll_Lock to
scroll-lock-mode.  (Bug#6861)
* lisp/scroll-lock.el (scroll-lock-mode): Note that the binding will
not work if 'w32-scroll-lock-modifier' is non-nil.
* etc/NEWS: Announce it.

etc/NEWS

@@ -445,6 +445,11 @@ RGB triplets with a single hexadecimal digit per component.
 ---
 ** The toolbar now shows the equivalent key binding in its tooltips.
 
+---
+** 'scroll-lock-mode' is now bound to the 'Scroll_Lock' key globally.
+Note that this key binding will not work on MS-Windows systems if
+'w32-scroll-lock-modifier' is non-nil.
+
 
 * Editing Changes in Emacs 27.1
 

lisp/bindings.el

@@ -1054,6 +1054,7 @@ if `inhibit-field-text-motion' is non-nil."
 ;(define-key global-map [delete] 'backward-delete-char)
 
 ;; natural bindings for terminal keycaps --- defined in X keysym order
+(define-key global-map [Scroll_Lock]    'scroll-lock-mode)
 (define-key global-map [C-S-backspace]  'kill-whole-line)
 (define-key global-map [home]		'move-beginning-of-line)
 (define-key global-map [C-home]		'beginning-of-buffer)

lisp/scroll-lock.el

@@ -54,7 +54,10 @@
 When enabled, keys that normally move point by line or paragraph
 will scroll the buffer by the respective amount of lines instead
 and point will be kept vertically fixed relative to window
-boundaries during scrolling."
+boundaries during scrolling.
+
+Note that the default key binding to Scroll_Lock will not work on
+MS-Windows systems if `w32-scroll-lock-modifier' is non-nil."
   :lighter " ScrLck"
   :keymap scroll-lock-mode-map
   (if scroll-lock-mode