Test that hbitmap iter is resistant to bitmap resetting.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20170628120530.31251-5-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>