MFC r252380:
Unbreak "zfs jail" and "zfs unjail" (broken in stable/9 since r249643)

I missed to register zfs_ioc_jail and zfs_ioc_unjail as legacy ioctl's
with the new zfs_ioctl_register_legacy() function.

These operations do not modify pools or datasets so there is no need to
log them to pool history.

Reported by:	Alexander Leidinger <netchild@FreeBSD.org> on current@
(cherry picked from commit e9345dc8e4b904827c63d74657a9e6cb30e3c849)