[arch-dev-public] FFmpeg: drop deprecated libavresample

[Maxime Gauduin]

Hi guys,

libavresample was initially merged into ffmpeg to be a drop-in
replacement for libav, but was never maintained by ffmpeg itself in
favor of their own libswresample. According to upstream, libswresample
can do everything libavresample can do and more [1], plus libavresample
has been entirely deprecated at the end of last year [2].

Thus I would like to get rid of it in our package. Here are the
packages still linking to it in our repositories, trying to build
without libavresample gave mixed results:

ffms2 -> OK
libextractor -> NOK (looks unrelated) [3]
libmgba -> NOK (looks unrelated) [4]
libopenshot -> NOK [5]
openscenegraph -> OK
performous -> NOK [6]
qtav -> OK

If there are no objection, I'll start a new TODO so we can work on
fixing the ones that don't build.

[1] 
https://lists.ffmpeg.org/pipermail/ffmpeg-devel/2012-April/123746.html
[2] https://patchwork.ffmpeg.org/patch/6959/
[3] 
https://buildbot.alucryd.xyz/#/builders/109/builds/2/steps/8/logs/stdio
[4] 
https://buildbot.alucryd.xyz/#/builders/108/builds/1/steps/8/logs/stdio
[5] 
https://buildbot.alucryd.xyz/#/builders/105/builds/1/steps/9/logs/stdio
[6] 
https://buildbot.alucryd.xyz/#/builders/104/builds/1/steps/9/logs/stdio

Cheers,
-- 
Maxime