Move the target bpftool build out of linux-tools so that it is
up to date.
This also fixes build issues due to differences between kernel
versions. The latest version should be fully backwards compatible.
The host bpftool is needed for enabling features such as the systemd
bpf-framework (to be added in a future patch).
Use the git download method to get the libbpf submodule.
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
3675131e6c