input: remove GDK backend check

We only support 'x11' for the time being.

re #27

src/input.c

@@ -61,24 +61,6 @@ static gboolean get_are_some_grabbed(GromitData *data)
 
 void setup_input_devices (GromitData *data)
 {
-  /*
-     first, check platform
-  */
-  gchar *backend;
-  g_printerr("Supported backends: ");
-#ifdef GDK_WINDOWING_X11
-  g_printerr("x11 ");
-  if (GDK_IS_X11_DISPLAY(data->display))
-    backend = "x11";
-#endif
-#ifdef GDK_WINDOWING_WAYLAND
-  g_printerr("wayland ");
-  if (GDK_IS_WAYLAND_DISPLAY(data->display))
-    backend = "wayland";
-#endif
-  g_printerr("\nUsing backend: %s\n", backend);
-
-
   /* ungrab all */
   release_grab (data, NULL);