devel: Don't run hardlink if rpm-ostree is in use
OSTree is a far, far more sophisticated wrapper around the `link()`
system call than the `hardlink` package - it supports using
as a mechanism for transactional offline updates, fetching over
HTTP with GPG signatures and deltas, etc. rpm-ostree uses it
Having the `kernel-devel` package run `hardlink` just adds
latency to `rpm-ostree compose tree` unnecessarily.