missing include

Former-commit-id: 4220a5f1694b249e033fa1ac38e1383d76c7a2f9

include/igl/copyleft/cgal/fast_winding_number.cpp

@@ -1,3 +1,4 @@
+#include "fast_winding_number.h"
 #include "../../fast_winding_number.h"
 #include "../../octree.h"
 #include "../../knn.h"