'tar --keep-old-files' causes exit code 2, revert back to '--skip-old-files' (#78)
'tar --keep-old-files' causes exit code 2, revert back to '--skip-old-files' (#78)

Because of '-keep-old-files', build.sh could only be run once.
Subsequent runs would stop on trying to extract the first download.
zimbatm/ffmpeg-static,zimbatm/ffmpeg-static