Don't remove last point in libedit

SHAPE_LINE_CHAIN in libedit doesn't make a polygon, so we always need
the last point and it shouldn't be closed

Fixes https://gitlab.com/kicad/code/kicad/issues/9934

eeschema/lib_shape.h

@@ -74,7 +74,11 @@ public:
     void BeginEdit( const wxPoint& aStartPoint ) override  { beginEdit( aStartPoint ); }
     bool ContinueEdit( const wxPoint& aPosition ) override { return continueEdit( aPosition ); }
     void CalcEdit( const wxPoint& aPosition ) override     { calcEdit( aPosition ); }
-    void EndEdit() override                                { endEdit(); }
+
+    /**
+     * The base EndEdit() removes the last point in the polyline, so don't call that here
+     */
+    void EndEdit() override                                { }
     void SetEditState( int aState )                        { setEditState( aState ); }
 
     void AddPoint( const wxPoint& aPosition );