Kodi started using features from ffmpeg 3.0 and fails to compile with any older version, so the dependency should be updated to reflect that.
Maybe kodi could just get a system-ffmpeg flag like some other packages have. (maybe some other libs that they also recommend not using system libs for ...)
This was fixed in #581276, or gitsha 0eddc97ea13728522af398ff0cdd903ea6e1034c