apparmor: do not expose kernel stack

commit f4ee2def2d70692ccff0d55353df4ee594fd0017 upstream.

Do not copy uninitalized fields th.td_hilen, th.td_data.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>