initctl: ignore possibly missing cpu.stat in cgroup2 root
initctl: ignore possibly missing cpu.stat in cgroup2 root

Older kernels (4.19) don't have the summary cpu.stat in the cgroup2
root, so let's ignore that problem and return zero.

Signed-off-by: Joachim Wiberg <583c295fd7602c168ad814279bbc3894ba65f5d6@gmail.com>

troglobit/finit,troglobit/finit