Have a memblock queue on the client side during recording. This makes the

Have a memblock queue on the client side during recording. This makes the
record callback optional in stead of mandatory.

For applications that wish to retain the old behaviour, simply call
pa_stream_peek() followed by pa_stream_drop() in the callback.

git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@507 fefdeb5f-60dc-0310-8127-8f9354f1896f