I noticed from
https://github.com/Homebrew/homebrew-core/actions/runs/5751070010 that
we're no longer creating reproducible bottles between macOS and Linux.
All macOS checksums have changed but Linux ones have not. The main
difference between the two platforms is the `gtar` version used so let's
always just use the formula on both platforms.
While we're here, clear up the ordering and comments a little on the
reproducible `tar` arguments so that it's easier to compare with the
reproducible builds archives documentation.
