update swig on windows

winx64/bin/swigwin-4.0.0/Examples/contract/simple_cxx/example.i

@@ -0,0 +1,28 @@
+%module example
+
+%contract Circle::Circle(double radius) {
+require:
+    radius > 0;
+}
+
+%contract Circle::area(void) {
+ensure:
+    area > 0;
+}
+
+%contract Shape::move(double dx, double dy) {
+require:
+    dx > 0;
+}
+
+/* should be no effect, since there is no move() for class Circle */
+%contract Circle::move(double dx, double dy) {
+require:
+    dy > 1;
+}
+
+# include must be after contracts
+%{
+#include "example.h"
+%}
+%include "example.h"