qapi: add native list coverage for visitor serialization tests Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Amos Kong <akong@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>