VAAPI-X11: Check return value of CreateWindow()

CreateWindow() returned VLC_SUCCESS, which was interpreted to take the
fail-path instead of checking for NOT VLC_SUCCESS.

modules/codec/avcodec/vaapi_x11.c

@@ -469,7 +469,7 @@ int OpenVaapiX11 (vlc_object_t *obj)
     xcb_visualid_t visual = wa->visual;
     free (wa);
 #endif
-    if (!CreateWindow(vd, conn, depth, 0 /* ??? */, width, height))
+    if (CreateWindow(vd, conn, depth, 0 /* ??? */, width, height) != VLC_SUCCESS)
     {
         msg_Err (vd, "cannot create VAAPI-X11 window");
         goto error;