GoLang:fix overload functions with polymorphic issue

Examples/test-suite/go/overload_polymorphic_runme.go

@@ -0,0 +1,11 @@
+package main
+
+import "./overload_polymorphic"
+
+func main(){
+	t := overload_polymorphic.NewDerived()
+	
+	if overload_polymorphic.Test(t) != 0 {
+		panic("failed")
+	}
+}