The test uses some questionable binary math. Rewrite it in a more explicit fashion.
This changes the prototype of uv_run() from: int uv_run(uv_loop_t* loop); To: int uv_run(uv_loop_t* loop, uv_run_mode mode); Where `mode` is UV_RUN_DEFAULT, UV_RUN_ONCE or UV_RUN_NOWAIT. Fixes #683.