[vino] Return error if X11 is not detected

[Ondrej Holy <oholy src gnome org>]

commit d5b743b11a6f102353af719fa34abd5e6c679e77
Author: Ondrej Holy <oholy redhat com>
Date:   Tue Feb 20 12:26:18 2018 +0100

    Return error if X11 is not detected
    
    Vino-server crashes on Wayland in XQueryExtension. Since vino-server is
    not expected to work on displays other than X11, let's exit immediately
    if GDK_IS_X11_DISPLAY fail.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=761120

 server/vino-main.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/server/vino-main.c b/server/vino-main.c
index dd95de7..7be3fff 100644
--- a/server/vino-main.c
+++ b/server/vino-main.c
@@ -28,6 +28,7 @@
 #include <glib/gi18n.h>
 #include <gtk/gtk.h>
 #include <locale.h>
+#include <gdk/gdkx.h>
 
 #include "vino-input.h"
 #include "vino-mdns.h"
@@ -273,6 +274,12 @@ main (int argc, char **argv)
     g_option_context_free (context);
   }
 
+  if (!GDK_IS_X11_DISPLAY (gdk_display_get_default ()))
+    {
+      g_printerr ("X11 is not detected\n");
+      return 1;
+    }
+
   /* GSettings */
   vino.settings = g_settings_new ("org.gnome.Vino");