Added cache for sequential printing clearance contours into class Print to avoid calculate them twice when needed.

-Fixed conflicts after cherry-picking 056d703573

src/libslic3r/Print.hpp

@@ -609,6 +609,7 @@ public:
     const PrintRegion&          get_print_region(size_t idx) const  { return *m_print_regions[idx]; }
     const ToolOrdering&         get_tool_ordering() const { return m_wipe_tower_data.tool_ordering; }
 
+    const Polygons& get_sequential_print_clearance_polygons() const { return m_sequential_print_clearance_polygons; }
     static bool sequential_print_horizontal_clearance_valid(const Print& print, Polygons* polygons = nullptr);
 
 protected:
@@ -658,6 +659,9 @@ private:
     // Estimated print time, filament consumed.
     PrintStatistics                         m_print_statistics;
 
+    // Cache to store sequential print clearance polygons
+    Polygons m_sequential_print_clearance_polygons;
+
     // To allow GCode to set the Print's GCodeExport step status.
     friend class GCode;
     // To allow GCodeProcessor to emit warnings.