BBufferConsumer::BufferReceived() cannot know whom to send the "buffer is
late" notification (unless we only have a single input). To solve this, the
media_header now contains extra fields that can be used to create a
media_source object.
* Unfortunately, BBufferProducer::SendBuffer() cannot know the output either in
case there is more than one. Hence, I deprecated the existing SendBuffer()
call and moved it into "private" - IOW old sources using it won't compile
anymore under Haiku.
* I introduced a new SendBuffer() variant that also gets the media_source as
argument.
* Updated all sources (that are part of the image) to use the new variant.
* Removed some purposely commented out code in the audio mixer.
* Implemented late buffer notification, as well as late buffer handling in the
audio mixer; this is a bit of work in progress, so the debug output is left
in there.
* Some cleanup.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@36184 a95241bf-73f2-0310-859d-f6bbb57e9c96
