ffmpeg: add ffmpeg-1.2 support if build with XBMA=master

Signed-off-by: Stephan Raue <stephan@openelec.tv>
xbmc: update to xbmc-74fa128

Signed-off-by: Stephan Raue <stephan@openelec.tv>
Merge branch 'master' of github.com:OpenELEC/OpenELEC.tv