freetdm: fix windows compilation

libs/freetdm/src/ftdm_sched.c

@@ -370,7 +370,7 @@ done:
 	UNREFERENCED_PARAMETER(ms);
 	UNREFERENCED_PARAMETER(callback);
 	UNREFERENCED_PARAMETER(data);
-	UNREFERENCED_PARAMETER(timer);
+	UNREFERENCED_PARAMETER(timerid);
 #endif
 	return status;
 }