Right now there is no way to query whether BPF programs are
attached to a sockmap or not.

we can use the standard interface in libbpf to query, such as:
bpf_prog_query(mapFd, BPF_SK_SKB_STREAM_PARSER, 0, NULL, ...);
the mapFd is the fd of sockmap.
Signed-off-by: NDi Zhu <zhudi2@huawei.com>
Acked-by: NYonghong Song <yhs@fb.com>
Reviewed-by: NJakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/r/20220119014005.1209-1-zhudi2@huawei.comSigned-off-by: NAlexei Starovoitov <ast@kernel.org>