message: Update gltfpack.cpp
  Use cgltf enum instead of a hard coded constant
diff: @@ -529,7 +529,7 @@ static void process(cgltf_data* data, const char* input_path, const char* output
  append(json_meshes, "{\"attributes\":{");
  writeMeshAttributes(json_meshes, views, json_accessors, accr_offset, prim, 0, qp, qt, settings);
  append(json_meshes, "}");
  - if (prim.type != 4)
  + if (prim.type != cgltf_primitive_type_triangles)
  {
  append(json_meshes, ",\"mode\":");
  append(json_meshes, size_t(prim.type));
  