Add unit tests for both resv_region_list_insert() and
range_inverse_array().

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: "Michael S. Tsirkin" <mst@redhat.com>
[ clg: Removal of unused variable in compare_ranges() ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>