LGTM: build libbpf
LGTM: build libbpf

libbpf is now required so it must be installed from source in LGTM (as
it is not available as a package on the Ubuntu version used by LGTM).

iovisor/bpftrace,iovisor/bpftrace,iovisor/bpftrace,iovisor/bpftrace