[archiso] Update fstab and "source dev" of aufs.
* Change from none -> union (looks like util-linux is confused BUG?) Avoid the message: "umount aufs failed: not found" at shutdown. #1 mount -t tmpfs none /something #2 mount -t tmpfs xxxx /something The output of findmnt -rnu -o SOURCE will be blank in #1 . * Change from aufs -> auto, make its more generic. * Update devpts and shm entries. Signed-off-by: Gerardo Exequiel Pozzi <email@example.com>