Test that hbitmap_next_zero and hbitmap_next_dirty_area can find things
after old bitmap end.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190805164652.42409-1-vsementsov@virtuozzo.com
Tested-by: John Snow <jsnow@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>