Wire up the use of a checkpoint list into each domain, similar to the
existing snapshot list.  This includes adding a function for checking
that a redefine operation fits in with the existing list, as well as
various filtering capabilities over the list contents.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>