socket closed after UnixStream::into_raw_fd()

[yshui]

UnixStream holds a IoHandle<mio_uds::UnixStream> which is not correctly disposed of in into_raw_fd, resulting in the returned file descriptor being closed when into_raw_fd returns, making the function useless.

[yshui]

I think the best way is to
impl<T: IntoRawFd> IntoRawFd for IoHandle<T> and use that, instead of keeping a copy of the RawFd.

[yshui]

This bug is reintroduced..