selftests/landlock: Test ioctl(2) and ftruncate(2) with open(O_PATH)

selftests/landlock: Test ioctl(2) and ftruncate(2) with open(O_PATH)

ioctl(2) and ftruncate(2) operations on files opened with O_PATH
should always return EBADF, independent of the
LANDLOCK_ACCESS_FS_TRUNCATE and LANDLOCK_ACCESS_FS_IOCTL_DEV access
rights in that file hierarchy.

Suggested-by: Mickaël Salaün <mic@digikod.net>
Signed-off-by: Günther Noack <gnoack@google.com>
Link: https://lore.kernel.org/r/20240419161122.2023765-5-gnoack@google.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>