4f7fb135bd
FreeBSD numbers `ZFS_IOC_*` starting at 0, so pick a different sentinel value to avoid unintentionally messing with `ZFS_IOC_POOL_CREATE` ioctls. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org> Closes #10729