Add xen-block-driver.0.2.0 and xen-disk.1.0.0
sync mirari with 0.9.5 upstream opam reqs
sync packages with upstream constraints, adjusted for 1.0.0
Add mirage-kfreebsd.1.0.0
mirage-xen: Mark mirage-kfreebsd conflicting.
mirage-unix: Mark mirage-kfreebsd conflicting.