Warn about :reverse-video in defface

This attribute keyword has been non-working in defface for 14 years,
thus warning about it is both safe and decent.

* lisp/emacs-lisp/bytecomp.el (bytecomp--check-cus-face-spec):
Warn and suggest :inverse-video to be used instead.
* test/lisp/emacs-lisp/bytecomp-tests.el (bytecomp-test-defface-spec):
Add a test case.
* etc/NEWS: Notify the user.

etc/NEWS

@@ -470,6 +470,10 @@ All the characters that belong to the 'symbol' script (according to
 
 * Lisp Changes in Emacs 31.1
 
+---
+** The face attribute ':reverse-video' is obsolete.
+Use ':inverse-video' instead.
+
 +++
 ** Support interactive D-Bus authorization.
 A new ':authorizable t' parameter has been added to 'dbus-call-method'

lisp/emacs-lisp/bytecomp.el

@@ -5396,15 +5396,18 @@ FORM is used to provide location, `bytecomp--cus-function' and
                             :underline :overline :strike-through :box
                             :inverse-video :stipple :font
                             ;; FIXME: obsolete keywords, warn about them too?
-                            ;; `:reverse-video' is very rare.
                             :bold           ; :bold t   = :weight bold
                             :italic         ; :italic t = :slant italic
-                            :reverse-video  ; alias for :inverse-video
                             ))
               (when (eq (car-safe val) 'quote)
                 (bytecomp--cus-warn
                  (list val atts sp spec)
                  "Value for face attribute `%s' should not be quoted" attr)))
+             ((eq attr :reverse-video)
+              (bytecomp--cus-warn
+               (list atts sp spec)
+               (concat "Face attribute `:reverse-video' is obsolete;"
+                       " use `:inverse-video' instead")))
              (t
               (bytecomp--cus-warn
                (list atts sp spec)

test/lisp/emacs-lisp/bytecomp-tests.el

@@ -2000,6 +2000,10 @@ EXPECTED-POINT BINDINGS (MODES \\='\\='(ruby-mode js-mode python-mode)) \
     (bytecomp--with-warning-test
      (rx "`:inverse' is not a valid face attribute keyword")
      (df '((t (:background "blue" :inverse t)))))  ; old attr list syntax
+    (bytecomp--with-warning-test
+     (rx "Face attribute `:reverse-video' is obsolete;"
+         " use `:inverse-video' instead")
+     (df '((t :background "red" :reverse-video t))))
     (bytecomp--with-warning-test
      (rx "Value for face attribute `:inherit' should not be quoted")
      (df '((t :inherit 'other))))