cmd: genutils: remove golint_failure entry

`golint` emits warnings

```
exported function OutDir should have comment or be unexported.
strings should not be capitalized or end with punctuation or a newline
```

- Add documentation comment to exported function OutDir.
- Remove newline from error string.
- Remove `hack\.golint_failures` entry for `cmd/genutils`

cmd/genutils/genutils.go

@@ -22,6 +22,8 @@ import (
 	"path/filepath"
 )
 
+// OutDir creates the absolute path name from path and checks path exists.
+// Returns absolute path including trailing '/' or error if path does not exist.
 func OutDir(path string) (string, error) {
 	outDir, err := filepath.Abs(path)
 	if err != nil {
@@ -34,7 +36,7 @@ func OutDir(path string) (string, error) {
 	}
 
 	if !stat.IsDir() {
-		return "", fmt.Errorf("output directory %s is not a directory\n", outDir)
+		return "", fmt.Errorf("output directory %s is not a directory", outDir)
 	}
 	outDir = outDir + "/"
 	return outDir, nil

hack/.golint_failures

@@ -1,5 +1,4 @@
 cluster/images/etcd-version-monitor
-cmd/genutils
 cmd/gke-certificates-controller/app
 cmd/hyperkube
 cmd/kube-controller-manager/app