ui: Mark the '-no-quit' option as deprecated

It's just a wrapper around the -display ...,window-close=off parameter,
and the name "no-quit" is rather confusing compared to "window-close"
(since there are still other means to quit the emulator), so we should
rather tell our users to use the "window-close" parameter instead.

While we're at it, update the documentation to state that
"-no-quit" is available for GTK, too, not only for SDL.

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210630163231.467987-4-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

docs/system/deprecated.rst

@@ -132,6 +132,12 @@ specified.
 Use ``-display sdl,window-close=...`` instead (i.e. with a minus instead of
 an underscore between "window" and "close").
 
+``-no-quit`` (since 6.1)
+''''''''''''''''''''''''
+
+The ``-no-quit`` is a synonym for ``-display ...,window-close=off`` which
+should be used instead.
+
 
 QEMU Machine Protocol (QMP) commands
 ------------------------------------

qemu-options.hx

@@ -1910,10 +1910,11 @@ SRST
 ERST
 
 DEF("no-quit", 0, QEMU_OPTION_no_quit,
-    "-no-quit        disable SDL window close capability\n", QEMU_ARCH_ALL)
+    "-no-quit        disable SDL/GTK window close capability (deprecated)\n", QEMU_ARCH_ALL)
 SRST
 ``-no-quit``
-    Disable SDL window close capability.
+    Disable window close capability (SDL and GTK only). This option is
+    deprecated, please use ``-display ...,window-close=off`` instead.
 ERST
 
 DEF("sdl", 0, QEMU_OPTION_sdl,

softmmu/vl.c

@@ -3237,6 +3237,8 @@ void qemu_init(int argc, char **argv, char **envp)
             case QEMU_OPTION_no_quit:
                 dpy.has_window_close = true;
                 dpy.window_close = false;
+                warn_report("-no-quit is deprecated, please use "
+                            "-display ...,window-close=off instead.");
                 break;
             case QEMU_OPTION_sdl:
 #ifdef CONFIG_SDL