selftests/bpf: Extend bind{4,6} programs with a call to bpf_setsockopt

To make sure it doesn't trigger sock_owned_by_me splat.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201202172516.3483656-4-sdf@google.com