Add test for self intersection

Author: stephomi

samples/models/self_intersectA.glb

@@ -255,3 +255,16 @@ TEST(Samples, Sponge4) {
 #endif
 }
 #endif
+
+#ifdef MANIFOLD_EXPORT
+TEST(Samples, SelfIntersect) {
+  manifold::PolygonParams().processOverlaps = true;
+  std::string file = __FILE__;
+  std::string dir = file.substr(0, file.rfind('/'));
+  Manifold m1 = ImportMesh(dir + "/../samples/models/self_intersectA.glb");
+  Manifold m2 = ImportMesh(dir + "/../samples/models/self_intersectB.glb");
+  Manifold res = m1 + m2;
+  res.GetMeshGL();  // test crash
+  manifold::PolygonParams().processOverlaps = false;
+}
+#endif