interaudio: Add option to enable/disable gap flags in nullsample buffers
Submitted by Carlos Rafael Giani
If the interaudio channel runs out of data, nullsample buffers are created.
interaudiosrc sets the GAP flag of these buffers. In some cases, it may
be preferable to not set the flag (for example, to produce one continuous
seamless stream even if the other side of the channel is currently paused).
One such case would be a system with a producer and a consumer pipeline, linked
together through an interaudio channel. The consumer pipeline always runs, while
the producer pipeline may sometimes be stopped, seeking, paused etc. In such a
case, it is necessary to make sure the consumer's interaudiosrc produces a
continuous stream. GAP flags would introduce unnecessary resynchronization events
inside the consumer pipeline's audio sink.