The container error integer field is currently used to store
the first error potentially encountered during any
vfio_listener_region_add() call. However this fails to propagate
detailed error messages up to the vfio_connect_container caller.
Instead of using an integer, let's use an Error handle.
Messages are slightly reworded to accomodate the propagation.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>