This makes the build more deterministic. Previously, nfd just blindly
took the tip revision from intel-cmt-cat master branch which could brake
the build without any changes in nfd itself.
* Make rdt-discovery buildable outside hardcoded path
Do not assume that nfd sources always reside under hardcoded directory
"/go/src/github.com/kubernetes-incubator/node-feature-discovery/". This
makes it possible e.g. to build nfd locally outside the Docker
container.
* Do not hardcode the path for RDT helper binaries
Utilize the standard PATH env variable, instead.
