Sketcher: Fixing Polyline Arc Endpoint autoconstraints

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fixes #3091

Autoconstraints did not check whether the arc was CW or CCW, as such the autoconstraint on the second position was sometimes assigned to the start point.

src/Mod/Sketcher/Gui/CommandCreateGeo.cpp

@@ -1216,7 +1216,9 @@ public:
                 virtualsugConstr1 = sugConstr2; // these are the initial constraints for the next iteration.
 
                 if (sugConstr2.size() > 0) {
-                    createAutoConstraints(sugConstr2, getHighestCurveIndex(), Sketcher::end);
+                    createAutoConstraints(sugConstr2, getHighestCurveIndex(), 
+                                          (SegmentMode == SEGMENT_MODE_Arc && startAngle > endAngle) ?
+                                            Sketcher::start : Sketcher::end);
                     sugConstr2.clear();
                 }