enable StupidAI and EmptyAI for static AI

AI/EmptyAI/main.cpp

@@ -0,0 +1,28 @@
+/*
+ * main.cpp, part of VCMI engine
+ *
+ * Authors: listed in file AUTHORS in main folder
+ *
+ * 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 "CEmptyAI.h"
+
+std::set<CGlobalAI*> ais;
+extern "C" DLL_EXPORT int GetGlobalAiVersion()
+{
+	return AI_INTERFACE_VER;
+}
+
+extern "C" DLL_EXPORT void GetAiName(char* name)
+{
+	strcpy(name,NAME);
+}
+
+extern "C" DLL_EXPORT void GetNewAI(std::shared_ptr<CGlobalAI> &out)
+{
+	out = std::make_shared<CEmptyAI>();
+}