Wrong result of sym_difference.

To reproduce (polygon's point order doesn't matter):
```
namespace bg = boost::geometry;
namespace bgm = boost::geometry::model;

using cpt_t = bgm::point;
using cpo_t = bgm::polygon;
using cmpo_t = bgm::multi_polygon;

int main()
{
cpo_t a, b, c, d;
bg::read_wkt("POLYGON((25 0,0 15,30 15,22 10,25 0))", a);
bg::read_wkt("POLYGON((5 0,15 25,25 0,15 5,5 0))", b);
bg::read_wkt("POLYGON((15 0,17 10,10 15,20 15,25 25,30 15,40 15,32 10,35 0,25 5,15 0))", c);
bg::read_wkt("POLYGON((5 0,7 10,0 15,10 15,15 25,20 15,30 15,22 10,25 0,15 5,5 0))", d);
bg::correct(a);
bg::correct(b);
bg::correct(c);
bg::correct(d);

cmpo_t ab, abc, dc, abcdc;
bg::sym_difference(a, b, ab); // ok
bg::sym_difference(ab, c, abc); // ok
bg::sym_difference(d, c, dc); // ok
bg::sym_difference(abc, dc, abcdc); // wrong!
}
```

Wrong result for geometries:
```
abc = MULTIPOLYGON(((20 2.5,25 0,25 -8.8817841970012523e-16,20.454545454545453 2.7272727272727271,20 2.5)),((20 2.5,15.909090909090908 4.5454545454545459,15 0,20 2.5)),((20.454545454545453 2.7272727272727271,23.333333333333332 4.166666666666667,19 15,15 25,11 15,10.777777777777779 14.444444444444443,17 10,16.071428571428573 5.3571428571428577,20.454545454545453 2.7272727272727271)),((16.071428571428573 5.3571428571428577,8.870967741935484 9.67741935483871,5 0,15 5,15.90909090909091 4.5454545454545459,16.071428571428573 5.3571428571428577)),((23.333333333333332 4.166666666666667,25 0,23.695652173913043 4.3478260869565215,23.333333333333332 4.166666666666667)),((10.777777777777779 14.444444444444443,10 15,0 15,8.870967741935484 9.67741935483871,10.777777777777779 14.444444444444443)),((23.695652173913043 4.3478260869565215,25 5,35 0,32 10,40 15,30 15,22 10,23.695652173913043 4.3478260869565215)),((30 15,25 25,20 15,30 15)))
dc = MULTIPOLYGON(((20 15,15 25,10 15,20 15)),((20 15,30 15,25 25,20 15)),((15.90909090909091 4.5454545454545459,17 10,10 15,0 15,7 10,5 0,15 5,15.90909090909091 4.5454545454545459)),((15.90909090909091 4.5454545454545459,15 0,20 2.5,15.90909090909091 4.5454545454545459)),((20 2.5,25 0,23.695652173913043 4.3478260869565215,20 2.5)),((23.695652173913043 4.3478260869565215,25 5,35 0,32 10,40 15,30 15,22 10,23.695652173913043 4.3478260869565215)))
```

Visual help: