selftests/bpf: Test for get_netns_cookie

Add test to use get_netns_cookie() from BPF_PROG_TYPE_SK_MSG.

Signed-off-by: Xu Liu <liuxu623@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210820071712.52852-3-liuxu623@gmail.com

selftests/bpf: Test for get_netns_cookie

Add test to use get_netns_cookie() from BPF_PROG_TYPE_SOCK_OPS.

Signed-off-by: Xu Liu <liuxu623@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210818105820.91894-3-liuxu623@gmail.com