This is needed to make the libavfilter framework work with audio
filters.

In particular add a type field to AVFilterLink, change the field types:
enum PixelFormat format   -> int format   in AVFilterBuffer
enum PixelFormat *formats -> int *formats in AVFilterFormats
enum PixelFormat *format  -> int format   in AVFilterLink

and change the function signatures:
AVFilterFormats *avfilter_make_format_list(const enum PixelFormat *pix_fmts); ->
AVFilterFormats *avfilter_make_format_list(const int *fmts);

int avfilter_add_colorspace(AVFilterFormats **avff, enum PixelFormat pix_fmt); ->
int avfilter_add_format(AVFilterFormats **avff, int fmt);

AVFilterFormats *avfilter_all_colorspaces(void); ->
AVFilterFormats *avfilter_all_formats(enum AVMediaType type);

This change breaks libavfilter API/ABI.

Patch by S.N. Hemanth Meenakshisundaram |smeenaks|ucsd|edu|.

Originally committed as revision 24424 to svn://svn.ffmpeg.org/ffmpeg/trunk