Older GCC (<4.8) isn't smart enough to optimize !__builtin_constant_p()
branch in bpf_htons.
I recently fixed it for pkt_v4 and pkt_v6 in commit 
a0517a0f7ef23
("selftests/bpf: use __bpf_constant_htons in test_prog.c"), but
later added another bunch of bpf_htons in commit 
bf0f0fd939451
("selftests/bpf: add simple BPF_PROG_TEST_RUN examples for flow
dissector").
Fixes: bf0f0fd939451 ("selftests/bpf: add simple BPF_PROG_TEST_RUN examples for flow dissector")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
 
        .thoff = sizeof(struct iphdr),
        .addr_proto = ETH_P_IP,
        .ip_proto = IPPROTO_TCP,
-       .n_proto = bpf_htons(ETH_P_IP),
+       .n_proto = __bpf_constant_htons(ETH_P_IP),
 };
 
 static struct bpf_flow_keys pkt_v6_flow_keys = {
        .thoff = sizeof(struct ipv6hdr),
        .addr_proto = ETH_P_IPV6,
        .ip_proto = IPPROTO_TCP,
-       .n_proto = bpf_htons(ETH_P_IPV6),
+       .n_proto = __bpf_constant_htons(ETH_P_IPV6),
 };
 
 static void test_flow_dissector(void)