By this it is possible to read and check just the first u64 of the corresponding
structs in order to identify the items.
This is needed for the fuse implementation in order to get entries based on the
archive offset, used as inode.
Directories are referenced by the offset to the goodbye tail while other items
are referenced by the offset of the filename followed by the entry.
Signed-off-by: Christian Ebner <c.ebner@proxmox.com>