1. added oss as a audio output target. direct write to device. like /dev...

1. added oss as a audio output target. direct write to device. like /dev/dsp or /dev/audio.
2. added a parameter. -i to set mDNS announce source interface ip.
3. add ".local" to hostname when create mDNS announcement
4. check if ifa->ifa_addr is NULL in mdns_tinysvcmdns.c.
5. use pthread_kill to abort voice play. audio_pipe or audio_oss might hang at "write" if not send USR1 signal.
6. exit rtsp reading while receive EINTR error. this is how we finish reading by send USR1 signal to reading thread.