Narrow the test target to testable code.

Generated code in pkg/apis and pkg/client has no tests, and fails
golint noisily, but none of it is actionable.

Makefile

@@ -67,9 +67,11 @@ k8s-ingress: build
 	CGO_ENABLED=0 GOOS=linux vgo build -o k8s-ingress cmd/*.go
 
 check: build
-	golint ./pkg/...
+	golint ./pkg/controller/...
+	golint ./pkg/interfaces/...
+	golint ./pkg/varnish/...
 	golint ./cmd/...
-	vgo test -v $(CODE_SUBDIRS)
+	vgo test -v ./pkg/controller/... ./pkg/interfaces/... ./pkg/varnish/...
 
 test: check