selftests/bpf: Fix build errors if CONFIG_NF_CONNTRACK=m

If CONFIG_NF_CONNTRACK=m, there are no definitions of NF_NAT_MANIP_SRC
and NF_NAT_MANIP_DST in vmlinux.h, build test_bpf_nf.c failed.

$ make -C tools/testing/selftests/bpf/

  CLNG-BPF [test_maps] test_bpf_nf.bpf.o
progs/test_bpf_nf.c:160:42: error: use of undeclared identifier 'NF_NAT_MANIP_SRC'
                bpf_ct_set_nat_info(ct, &saddr, sport, NF_NAT_MANIP_SRC);
                                                       ^
progs/test_bpf_nf.c:163:42: error: use of undeclared identifier 'NF_NAT_MANIP_DST'
                bpf_ct_set_nat_info(ct, &daddr, dport, NF_NAT_MANIP_DST);
                                                       ^
2 errors generated.

Copy the definitions in include/net/netfilter/nf_nat.h to test_bpf_nf.c,
in order to avoid redefinitions if CONFIG_NF_CONNTRACK=y, rename them with
___local suffix. This is similar with commit 1058b6a7 ("selftests/bpf:
Do not fail build if CONFIG_NF_CONNTRACK=m/n").

Fixes: b06b45e8 ("selftests/bpf: add tests for bpf_ct_set_nat_info kfunc")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/1674028604-7113-1-git-send-email-yangtiezhu@loongson.cnSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

tools/testing/selftests/bpf/progs/test_bpf_nf.c

@@ -34,6 +34,11 @@ __be16 dport = 0;
 int test_exist_lookup = -ENOENT;
 u32 test_exist_lookup_mark = 0;
 
+enum nf_nat_manip_type___local {
+	NF_NAT_MANIP_SRC___local,
+	NF_NAT_MANIP_DST___local
+};
+
 struct nf_conn;
 
 struct bpf_ct_opts___local {
@@ -58,7 +63,7 @@ int bpf_ct_change_timeout(struct nf_conn *, u32) __ksym;
 int bpf_ct_set_status(struct nf_conn *, u32) __ksym;
 int bpf_ct_change_status(struct nf_conn *, u32) __ksym;
 int bpf_ct_set_nat_info(struct nf_conn *, union nf_inet_addr *,
-			int port, enum nf_nat_manip_type) __ksym;
+			int port, enum nf_nat_manip_type___local) __ksym;
 
 static __always_inline void
 nf_ct_test(struct nf_conn *(*lookup_fn)(void *, struct bpf_sock_tuple *, u32,
@@ -157,10 +162,10 @@ nf_ct_test(struct nf_conn *(*lookup_fn)(void *, struct bpf_sock_tuple *, u32,
 
 		/* snat */
 		saddr.ip = bpf_get_prandom_u32();
-		bpf_ct_set_nat_info(ct, &saddr, sport, NF_NAT_MANIP_SRC);
+		bpf_ct_set_nat_info(ct, &saddr, sport, NF_NAT_MANIP_SRC___local);
 		/* dnat */
 		daddr.ip = bpf_get_prandom_u32();
-		bpf_ct_set_nat_info(ct, &daddr, dport, NF_NAT_MANIP_DST);
+		bpf_ct_set_nat_info(ct, &daddr, dport, NF_NAT_MANIP_DST___local);
 
 		ct_ins = bpf_ct_insert_entry(ct);
 		if (ct_ins) {