Fix broken chess960 under Shredder GUI

We need to add a dummy option anyway to make GUIs happy.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/ucioption.cpp

@@ -131,6 +131,7 @@ namespace {
     o["Emergency Base Time"] = Option(200, 0, 60000);
     o["Emergency Move Time"] = Option(70, 0, 5000);
     o["Minimum Thinking Time"] = Option(20, 0, 5000);
+    o["UCI_Chess960"] = Option(false); // Just a dummy but needed by GUIs
     o["UCI_AnalyseMode"] = Option(false);
 
     // Any option should know its name so to be easily printed