Fix -Wclass-memaccess warning

Replace C-style memset with C++ value-initialization/assignment (smarter and safer: see https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#slcon3-avoid-bounds-errors)

src/Mod/Path/libarea/clipper.cpp

@@ -64,24 +64,24 @@ static int const Skip = -2;        //edge that would otherwise close a path
 #define NEAR_ZERO(val) (((val) > -TOLERANCE) && ((val) < TOLERANCE))
 
 struct TEdge {
-  IntPoint Bot;
-  IntPoint Curr;
-  IntPoint Top;
-  IntPoint Delta;
-  double Dx;
-  PolyType PolyTyp;
-  EdgeSide Side;
-  int WindDelta; //1 or -1 depending on winding direction
-  int WindCnt;
-  int WindCnt2; //winding count of the opposite polytype
-  int OutIdx;
-  TEdge *Next;
-  TEdge *Prev;
-  TEdge *NextInLML;
-  TEdge *NextInAEL;
-  TEdge *PrevInAEL;
-  TEdge *NextInSEL;
-  TEdge *PrevInSEL;
+  IntPoint Bot{0,0};
+  IntPoint Curr{0,0};
+  IntPoint Top{0,0};
+  IntPoint Delta{0,0};
+  double Dx = 0.0;
+  PolyType PolyTyp = ptSubject;
+  EdgeSide Side = esLeft;
+  int WindDelta = 0; //1 or -1 depending on winding direction
+  int WindCnt = 0;
+  int WindCnt2 = 0; //winding count of the opposite polytype
+  int OutIdx = 0;
+  TEdge *Next = nullptr;
+  TEdge *Prev = nullptr;
+  TEdge *NextInLML = nullptr;
+  TEdge *NextInAEL = nullptr;
+  TEdge *PrevInAEL = nullptr;
+  TEdge *NextInSEL = nullptr;
+  TEdge *PrevInSEL = nullptr;
 };
 
 struct IntersectNode {
@@ -715,7 +715,6 @@ void DisposeOutPts(OutPt*& pp)
 
 inline void InitEdge(TEdge* e, TEdge* eNext, TEdge* ePrev, const IntPoint& Pt)
 {
-  std::memset(e, 0, sizeof(TEdge));
   e->Next = eNext;
   e->Prev = ePrev;
   e->Curr = Pt;