Fixed bug that caused an infinite loop, compare delfrrr/delaunator-cp…

…p#32

src/lib/Delaunator2D.cpp

@@ -452,7 +452,7 @@ std::size_t Delaunator2D::legalize(std::size_t a) {
 						hull_tri[e] = a;
 						break;
 					}
-					e = hull_next[e];
+					e = hull_prev[e];
 				} while (e != hull_start);
 			}
 			link(a, hbl);