Merge branch 'bpf-convert-more-samples'

Jakub Kicinski says:

====================
This set converts xdpsock_user.c and xdp_fwd_user.c to use libbpf instead
of bpf_load.o.  First two patches are minor improvements to libbpf to make
the conversion (and use of libbpf in general) nicer.
====================

Acked-by: Yonghong Song <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>