pulsesrc: fix checking for invalid stream index
PA_INVALID_INDEX, the default value, is unfortunately !0. Setting the volume before the stream is created will put the ring buffer in error state. Unfortunately, that's what spice-gtk does.
PA_INVALID_INDEX, the default value, is unfortunately !0. Setting the volume before the stream is created will put the ring buffer in error state. Unfortunately, that's what spice-gtk does.