Merge branch 'bpf-verifier-log-btf-prep'

Martin KaFai Lau says:

====================
This patch set has some changes and clean-up works for
the bpf_verifier_log.  They are the prep works for the
BTF (BPF Type Format).
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>