selftests/bpf: allow specifying helper for BPF_SK_LOOKUP

Make the BPF_SK_LOOKUP macro take a helper function, to ease
writing tests for new helpers.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
3 files changed