selftests/bpf: Remove bpf_tcp_helpers.h usages from other misc bpf tcp-cc tests

This patch removed the final few bpf_tcp_helpers.h usages
in some misc bpf tcp-cc tests and replace it with
bpf_tracing_net.h (i.e. vmlinux.h)

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240509175026.3423614-9-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests/bpf: Sanitize the SEC and inline usages in the bpf-tcp-cc tests

It is needed to remove the BPF_STRUCT_OPS usages from the tcp-cc tests
because it is defined in bpf_tcp_helpers.h which is going to be retired.
While at it, this patch consolidates all tcp-cc struct_ops programs to
use the SEC("struct_ops") + BPF_PROG().

It also removes the unnecessary __always_inline usages from the
tcp-cc tests.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240509175026.3423614-5-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf: selftests: Add dctcp fallback test

This patch makes the bpf_dctcp test to fallback to cubic by
using setsockopt(TCP_CONGESTION) when the tcp flow is not
ecn ready.

It also checks setsockopt() is not available to release().

The settimeo() from the network_helpers.h is used, so the local
one is removed.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210824173026.3979130-1-kafai@fb.com