Fix chamfered cyl() orientation for odd $fn

shapes3d.scad

@@ -1522,7 +1522,8 @@ module cyl(
                     [0,l/2]
                 ];
 
-                rotate_extrude(convexity=2) polygon(path);
+                vnf = rotate_sweep(path);
+                vnf_polyhedron(vnf, convexity=2);
             }
         }
         children();