build: clear 31 warnings - copy and move declarations (#15507)

src/libslic3r/Support/SupportCommon.cpp

@@ -1234,10 +1234,6 @@ static void modulate_extrusion_by_overlapping_layers(
                 (fragment_end.is_start ? &polyline.points.front() : &polyline.points.back());
         }
     private:
-        ExtrusionPathFragmentEndPointAccessor& operator=(const ExtrusionPathFragmentEndPointAccessor&) {
-            return *this;
-        }
-
         const std::vector<ExtrusionPathFragment> &m_path_fragments;
     };
     const coord_t search_radius = 7;