samples don't build on v4.18

From: Joel Fernandes
Date: Tue Aug 14 2018 - 21:21:38 EST

When building BPF samples on v4.18, I get the following errors:

$ cd samples/bpf/
$ make

Auto-detecting system features:
... libelf: [ OFF ]
... bpf: [ OFF ]

No libelf found
Makefile:213: recipe for target 'elfdep' failed

I bissected it down to commit 5f9380572b4bb24f60cd492b1

Author: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
Date: Thu May 10 10:24:39 2018 -0700

samples: bpf: compile and link against full libbpf

Checking out a kernel before this commit makes the samples build. Also I do
have libelf on my system.

Any thoughts on this issue?

thank you,

- Joel