Merge branch 'bpf-drop-libbpf-from-preload'

Alexei Starovoitov says:

====================
CO-RE in the kernel support allows bpf preload to switch to light
skeleton and remove libbpf dependency.

This reduces the size of bpf_preload_umd from 300kbyte to 19kbyte
and eventually will make "kernel skeleton" possible.
====================

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