Not strictly needed, but it simplifies the packaging to do so and it
unbreaks the build.
Signed-off-by: NFelix Abecassis <fabecassis@nvidia.com>

Tools like CRI-O or Red Hat's fork of Docker only need the OCI hook,
not the full runtime.

The hook is also likely to move at a different cadence than the full
runtime, which is tied to the upstream Docker releases.