This includes disabling some features in the initrd by default, this is
only done when the new initrd is used. Namely, ext and bcache are
disabled by default. bcache gets an own enable option while ext is
detected like any other filesystem.
Adds /dev/disk/by-{id,label}/* symlinks for bcache device nodes, in the
final rootfs.
Symlinks will only be created for bcache devices that contain
filesystems. So if you have a blank bcache device or run LVM on top of
bcache you will not get this kind of symlink.
