DllAvFilter.h: Do not map avfilter_open.
It is deprecated in FFmpeg git master and unused in xbmc code.
DllAvUtil.h: Add LIBAVUTIL_FROM* macros.
DllAvUtil.h: Map av_frame_free when applicable.
DllAvUtil.h: Map av_frame_alloc when applicable.
DllAvUtil.h: Map av_frame_unref when applicable.
DllAvUtil.h: Map av_frame_move_ref when applicable.
Switch to the avframe based API for libavfilter when it is available.

The old API is deprecated and the new code is simpler and saves a memcopy.
Also, use the AVFrame values instead of the codec context for DVDVideoCodecFFmpeg::GetPicture.
DllAvFilter: Map avfilter_graph_parse_ptr when available.
Use avfilter_graph_parse_ptr when available (Fixes a deprecation warning with FFmpeg 2.0).

Include the libav API for avfilter_graph_parse which should help porting to libav.
Drop support for av_vsrc_buffer_add_frame: We are using the new API since libavfilter 3, which is available in FFmpeg 1.0 at least.

libavfilter from libav will not work without the avframe based API anyway.
DllAvFilter.h: Include libavfilter/avfilter.h since we are using functions from this header such as avfilter_get_by_name.
DllAvFilter.h: Include libavfilter/avcodec.h only when necessary. We are not using it anymore when using the new avfilter APIs and it contains only deprecated functions.
Merge pull request #3013 from aballier/avfilter_deprec

Modernize libavfilter usage