SDL: convert to new package format

Signed-off-by: Stephan Raue <stephan@openelec.tv>
SDL_image: convert to new package format

Signed-off-by: Stephan Raue <stephan@openelec.tv>
libdrm: update to libdrm-2.4.52

Signed-off-by: Stephan Raue <stephan@openelec.tv>
ffmpeg: convert to new package format

Signed-off-by: Stephan Raue <stephan@openelec.tv>