Conditional compilation to exclude all Perl/XS stuff from C++ code

xs/src/Polyline.hpp

@@ -10,8 +10,11 @@ class Polyline : public MultiPoint {
     public:
     Point* last_point() const;
     void lines(Lines &lines) const;
+    
+    #ifdef SLIC3RXS
     SV* to_SV_ref();
     SV* to_SV_clone_ref() const;
+    #endif
 };
 
 typedef std::vector<Polyline> Polylines;