PulseAudio: add a "?" choice if our stream moves to an unknown sink
PulseAudio: add a "?" choice if our stream moves to an unknown sink

This happens if the stream to a device that appeared after the stream
was started.

vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,shyamalschandra/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,krichter722/vlc,xkfz007/vlc,vlc-mirror/vlc,krichter722/vlc,krichter722/vlc,krichter722/vlc,jomanmuk/vlc-2.1,shyamalschandra/vlc,vlc-mirror/vlc,krichter722/vlc,krichter722/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,vlc-mirror/vlc,shyamalschandra/vlc,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,vlc-mirror/vlc,shyamalschandra/vlc,shyamalschandra/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,xkfz007/vlc,shyamalschandra/vlc,xkfz007/vlc,vlc-mirror/vlc,shyamalschandra/vlc,xkfz007/vlc,xkfz007/vlc,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,xkfz007/vlc,krichter722/vlc