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>

selftests/bpf: Test a BPF CC implementing the unsupported get_info()

Test whether a TCP CC implemented in BPF providing get_info() is
rejected correctly. get_info() is unsupported in a BPF CC. The check for
required functions in a BPF CC has moved, this test ensures unsupported
functions are still rejected correctly.

Signed-off-by: Jörn-Thorben Hinz <jthinz@mailbox.tu-berlin.de>
Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220622191227.898118-6-jthinz@mailbox.tu-berlin.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>