This apparently manifests when one passes `--cpu=.5` to docker because
then /sys/fs/cgroup/cpu.max looks like `50000 100000`, and 50000 divided
by 100000 is zero when using integer math.
Return 1 in that case, indicating there is at least one CPU available.
Returning 0 makes no sense because there is always at least one CPU
available, otherwise the program wouldn't be running.
Fixes: https://github.com/nodejs/node/issues/59200
2e7c07f4d1