[oe] ext3 support

[Andrew Paulsen]

I don't know if anyone else is interested, but ext3 seems to work if
you add journaling to an ext2 rootfs image.  Here is my attempt at
supporting this from OpenEmbedded:

EXTRA_IMAGECMD_ext3 ?= ""
IMAGE_DEPENDS_ext3 = "genext2fs-native e2fsprogs-native"
IMAGE_CMD_ext3 = "genext2fs -b ${IMAGE_ROOTFS_SIZE} -d ${IMAGE_ROOTFS}
${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.rootfs.ext3; \
        tune2fs -j ${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.rootfs.ext3;
${EXTRA_IMAGECMD}"

It builds the depends and rootfs and the kernel recognizes it as an
ext3 file system.