Offline Build

As of v4.4, it is not possible to build MobileFFmpeg on a host without internet connection. The source code of ffmpeg is not included in the repository and a working internet connection is required to download it. Additionally, the source code of GPL licensed libraries (libvid.stab, rubberband, x264, x265 and xvidcore) is also not not stored in the repository. Again, a working internet connection is required to download the source code of those libraries.