The standard "fmt" target will also rewrite

Add return code, by checking for empty output

Also fix the broken fmt and reportcard ones:

Recursive variable 'SOURCE_DIRS' references itself (eventually).

Fix issue with exceeding shell command line length limits for certain setups.
https://git.buildroot.net/buildroot/tree/CHANGES?h=2018.05.x

making sure minikube is deleted before setup to avoid https://github.com/kubernetes/minikube/issues/4132

Not needed when using Go modules.

The default target (out/minikube) was replaced by "makedeploys",
that would always rebuild the deploy .yaml files from .template

Add helper for "go vet", and don't use the test files variable.

Also return an exit code from golint (why is this not default?)

Currently it is hardcoded to build for any GOOS, but same GOARCH.

Change this to allow building for any combination of: minikube-*-*

See https://goreportcard.com/report/github.com/kubernetes/minikube