Use OCCT Handle macro for Handle_ classes

This is the result of running OCCT's upgrade script provided
with OCCT 7.0. See
https://www.opencascade.com/content/freecad-occt710-and-windows-rtti-data-missing#comment-form
and
https://www.forum.freecadweb.org/viewtopic.php?f=4&t=21405&start=120#p169019
for why this is necessary for OCCT >= 7.1

src/Mod/Path/App/Area.cpp

@@ -1520,7 +1520,7 @@ struct ShapeInfo{
                 // PointProjectionFailed. Why??
 
                 Standard_Real first,last;
-                const Handle_Geom_Curve & curve = BRep_Tool::Curve(edge, first, last);
+                const Handle(Geom_Curve) & curve = BRep_Tool::Curve(edge, first, last);
                 pt = curve->Value(last);
                 bool reversed;
                 if(pprev.Distance(pt)<Precision::Confusion()) {