selftests/bpf: Fix a fd leak in error paths in open_netns

As Martin mentioned in review comment, there is an existing bug that
orig_netns_fd will be leaked in the later "goto fail;" case after
open("/proc/self/ns/net") in open_netns() in network_helpers.c. This
patch adds "close(token->orig_netns_fd);" before "free(token);" to
fix it.

Fixes: a30338840fa5 ("selftests/bpf: Move open_netns() and close_netns() into network_helpers.c")
Signed-off-by: Geliang Tang <[e-mail]>
Link: https://lore.kernel.org/r/a10[e-mail]
Signed-off-by: Martin KaFai Lau <[e-mail]>

tools/testing/selftests/bpf/network_helpers.c

···
 
 	return token;
 fail:
+	if (token->orig_netns_fd != -1)
+		close(token->orig_netns_fd);
 	free(token);
 	return NULL;
 }