tests: make sure tst-elf-permissions has GNU_RELRO segment

Tested-by: Claudio Fontana <claudio.fontana@huawei.com>
Reviewed-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>