Update to box2d 2.4.1

src/libraries/box2d/b2_polygon_shape.h

@@ -22,13 +22,14 @@
 #ifndef B2_POLYGON_SHAPE_H
 #define B2_POLYGON_SHAPE_H
 
+#include "b2_api.h"
 #include "b2_shape.h"
 
 /// A solid convex polygon. It is assumed that the interior of the polygon is to
 /// the left of each edge.
 /// Polygons have a maximum number of vertices equal to b2_maxPolygonVertices.
 /// In most cases you should not need many vertices for a convex polygon.
-class b2PolygonShape : public b2Shape
+class B2_API b2PolygonShape : public b2Shape
 {
 public:
 	b2PolygonShape();