wayland: Print an error when the display connection is closed by the …

…server

Otherwise, it isn't immediately clear to the client application as to why its windows suddenly disappeared, and it received a quit event out of nowhere.

src/video/wayland/SDL_waylandevents.c

@@ -498,6 +498,7 @@ void Wayland_PumpEvents(SDL_VideoDevice *_this)
          */
         if (!Wayland_VideoReconnect(_this)) {
             d->display_disconnected = 1;
+            SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Wayland display connection closed by server (fatal)");
 
             /* Only send a single quit message, as application shutdown might call
              * SDL_PumpEvents