zfs_handle used after being closed/freed in change_one callback

zfs_handle used after being closed/freed in change_one callback

This is a typical case of use after free. We would call zfs_close(zhp)
which would free the handle, and then call zfs_iter_children() on that
handle later.  This change ensures that the zfs_handle is only closed
when we are ready to return.

Running `zfs inherit -r sharenfs pool` was failing with an error
code without any error messages. After some debugging I've pinpointed
the issue to be memory corruption, which would cause zfs to try to
issue an ioctl to the wrong device and receive ENOTTY.

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Sebastien Roy <sebastien.roy@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alek Pinchuk <apinchuk@datto.com>
Signed-off-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Issue #7967
Closes #9165