Merge branch 'Teach libbpf to "fix up" BPF verifier log'

Andrii Nakryiko says:

====================

This patch set teaches libbpf to enhance BPF verifier log with human-readable
and relevant information about failed CO-RE relocation. Patch #9 is the main
one with the new logic. See relevant commit messages for some more details.

All the other patches are either fixing various bugs detected
while working on this feature, most prominently a bug with libbpf not handling
CO-RE relocations for SEC("?...") programs, or are refactoring libbpf
internals to allow for easier reuse of CO-RE relo lookup and formatting logic.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>