Merge branch 'bpf-libbpf-btf-parsing'

Andrii Nakryiko says:

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It's pretty common for applications to want to parse raw (binary) BTF data
from file, as opposed to parsing it from ELF sections. It's also pretty common
for tools to not care whether given file is ELF or raw BTF format. This patch
series exposes internal raw BTF parsing API and adds generic variant of BTF
parsing, which will efficiently determine the format of a given fail and will
parse BTF appropriately.

Patches #2 and #3 removes re-implementations of such APIs from bpftool and
resolve_btfids tools.
====================

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