Unbreak "zfs jail" and "zfs unjail" (broken since r248571)

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 <ale@FreeBSD.org> and others on current@
MFC after:	3 days
Check the return value from ath_hal_malloc()

Reported by:	uqs