Only generate .provided file when actually building a rootfs.
Only generate .provided file when actually building a rootfs.

jonasjonas/gentoo-bb,berney/gentoo-bb,edannenberg/gentoo-bb,guruvan/gentoo-bb,berney/gentoo-bb,edannenberg/kubler,jonasjonas/gentoo-bb,gdm/gentoo-bb,gdm/gentoo-bb,guruvan/gentoo-bb,edannenberg/gentoo-bb