[OE-core] [Openembedded-architecture] RFC: Split do_rootfs into image specific tasks?

[Richard Purdie]

To put this in a different why which people might be able to relate to,
this changes:

do_rootfs

into:

do_rootfs
do_image
do_image_ext4
do_image_tar
do_image_complete

(for IMAGE_FSTYPES = "tar.bz2 ext4")

Cheers,

Richard