busybox

volume_id: Adopt to new kbuild style.

Kbuild instructions for util-linux/volume_id are moved into the
source files according to the new build feature.

No code change.

Signed-off-by: Sven-Göran Bergh <sgb@systemasis.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>