Fixing the infill order for concentric infill to outside-in.

Relies to:
Concentric Fill Start Point - New Feature Request #4948
Feature Request: Archimedean Chords - Option to define direction of travel (Inside-Out or Outside-In) #5214

src/libslic3r/Fill/FillConcentric.hpp

@@ -8,7 +8,7 @@ namespace Slic3r {
 class FillConcentric : public Fill
 {
 public:
-    ~FillConcentric() override {}
+    ~FillConcentric() override = default;
 
 protected:
     Fill* clone() const override { return new FillConcentric(*this); };