Infrastructure

The current git bundles at https://dev-www.libreoffice.org/bundles/ and referenced at https://www.libreoffice.org/about-us/source-code/ don't seem to have been made with the git bundle create command.
This causes problems when trying to use them on Windows (https://github.com/git-for-windows/git/issues/1924#issuecomment-562981101).
Using that command would also "make everything a lot faster and smaller because the worktree files are skipped (and as a consequence, git status [would] not be dealing with totally bogus timestamps)".