fix CI build

AI/Nullkiller2/Engine/ResourceTrader.cpp

@@ -6,6 +6,7 @@
 * License: GNU General Public License v2.0 or later
 * Full text of license available in license.txt file, in main folder
 */
+#include "StdInc.h"
 #include "ResourceTrader.h"
 
 namespace NK2AI