package/ffmpeg: Add Kodi patchset

In the past xbmc delivered its own ffmpeg source code with specific patches to
address bugs found during the use of xbmc. For Helix the ffmpeg source code was
removed, Helix uses a vanilla ffmpeg source tarball and applies this patchset
on top of it.

Downloaded from
https://github.com/xbmc/FFmpeg/compare/FFmpeg:release/2.5...release/2.5-xbmc.patch



[Thomas: use individual patches instead.]

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>