1. Why is this change necessary ?
fixes: kubernetes/node-problem-detector#161
2. How does this change address the issue ?
Under package cmd/options, the testing for SetNodeNameOrDie need
to decide Nodename based on environment variable "NODE_NAME" or
hostname or hostnameoverride variable.
3. How to verify this change ?
Run "go test" with admin privilege
Signed-off-by: gkGaneshR <gkganesh126@gmail.com>