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>
diff --git a/qemu-options.hx b/qemu-options.hx
index ae56fa4..c862f1f 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1910,10 +1910,11 @@
 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,