Merge branch 'use network helpers, part 9'

Geliang Tang says:

====================
v3:
 - patch 2:
   - clear errno before connect_to_fd_opts.
   - print err logs in run_test.
   - set err to -1 when fd >= 0.
 - patch 3:
   - drop "int err".

v2:
 - update patch 2 as Martin suggested.

This is the 9th part of series "use network helpers" all BPF selftests
wide.

Patches 1-2 update network helpers interfaces suggested by Martin.
Patch 3 adds a new helper connect_to_addr_str() as Martin suggested
instead of adding connect_fd_to_addr_str().
Patch 4 uses this newly added helper in make_client().
Patch 5 uses make_client() in sk_lookup and drop make_socket().
====================

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