Merge branch 'use network helpers, part 8'

Geliang Tang says:

====================
v11:
 - new patches 2, 4, 6.
 - drop expect_errno from network_helper_opts as Eduard and Martin
   suggested.
 - drop sockmap_ktls patches from this set.

v10:
 - a new patch 10 is added.
 - patches 1-6, 8-9 unchanged, only commit logs updated.
 - "err = -errno" is used in patches 7, 11, 12 to get the real error
   number before checking value of "err".

v9:
 - new patches 5-7, new struct member expect_errno for network_helper_opts.
 - patches 1-4, 8-9 unchanged.
 - update patches 10-11 to make sure all tests pass.

v8:
 - only patch 8 updated, to fix errors reported by CI.

v7:
 - address Martin's comments in v6. (thanks)
 - use MAX(opts->backlog, 0) instead of opts->backlog.
 - use connect_to_fd_opts instead connect_to_fd.
 - more ASSERT_* to check errors.

v6:
 - update patch 6 as Daniel suggested. (thanks)

v5:
 - keep make_server and make_client as Eduard suggested.

v4:
 - a new patch to use make_sockaddr in sockmap_ktls.
 - a new patch to close fd in error path in drop_on_reuseport.
 - drop make_server() in patch 7.
 - drop make_client() too in patch 9.

v3:
 - a new patch to add backlog for network_helper_opts.
 - use start_server_str in sockmap_ktls now, not start_server.

v2:
 - address Eduard's comments in v1. (thanks)
 - fix errors reported by CI.

This patch set uses network helpers in sk_lookup, and drop the local
helpers inetaddr_len() and make_socket().
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>