message: libmesh: start background thread if requested in the environment
diff: using namespace mesh;
  static __attribute__((constructor)) void libmesh_init() {
  + char *bgThread = getenv("MESH_BACKGROUND_THREAD");
  + if (!bgThread)
  + return;
  +
  + int shouldThread = atoi(bgThread);
  + if (shouldThread)
  runtime().startBgThread();
  }
  