lavfi/buffersrc: set channel layout if it is known.

Introduced in 01649c7, lost in the API change.
lavfi/buffersrc: check channel count changes.
lavfi/buffersrc: disable deprecated warnings.
lavfi/buffersink: fix header.

Move non-obsolete functions, structures and constants outside
the scope of "#if FF_API_AVFILTERBUFFER".

Add attribute_deprecated to av_buffersink_get_buffer_ref()
and av_buffersink_poll_frame().

Add doxygen for av_buffersink_get_frame_flags().
Merge remote-tracking branch 'cigaes/master'

* cigaes/master:
  lavfi/buffersink: fix header.
  lavfi/buffersrc: disable deprecated warnings.
  lavfi/buffersrc: check channel count changes.
  lavfi/buffersrc: set channel layout if it is known.

Merged-by: Michael Niedermayer <michaelni@gmx.at>
mpeg: Add passing DVD navigation packets (startcode 0x1bf) to caller to allow better playback handling of DVDs.

The two types of packets (PCI and DSI) are passed untouched but combined by the new codec ID AV_CODEC_ID_DVD_NAV.
 The first 980 bytes in the packet contain the PCI data. The next 1018 are the DSI data.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Merge branch 'master' of git://git.videolan.org/ffmpeg