selftests/bpf: add btf annotations for cgroup_local_storage maps

Add btf annotations to cgroup local storage maps (per-cpu and shared)
in the network packet counting example.
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/netcnt_prog.c

@@ -16,12 +16,18 @@ struct bpf_map_def SEC("maps") percpu_netcnt = {
 	.value_size = sizeof(struct percpu_net_cnt),
 };
 
+BPF_ANNOTATE_KV_PAIR(percpu_netcnt, struct bpf_cgroup_storage_key,
+		     struct percpu_net_cnt);
+
 struct bpf_map_def SEC("maps") netcnt = {
 	.type = BPF_MAP_TYPE_CGROUP_STORAGE,
 	.key_size = sizeof(struct bpf_cgroup_storage_key),
 	.value_size = sizeof(struct net_cnt),
 };
 
+BPF_ANNOTATE_KV_PAIR(netcnt, struct bpf_cgroup_storage_key,
+		     struct net_cnt);
+
 SEC("cgroup/skb")
 int bpf_nextcnt(struct __sk_buff *skb)
 {