Nitpick plugin/manager.go: use loop to create directories

Instead of duplicating the same if condition per plugin manager directory,
use one if condition and a for-loop.

Signed-off-by: Boaz Shuster <ripcurld.github@gmail.com>

plugin/manager.go

@@ -107,14 +107,10 @@ func NewManager(config ManagerConfig) (*Manager, error) {
 	manager := &Manager{
 		config: config,
 	}
-	if err := os.MkdirAll(manager.config.Root, 0700); err != nil {
-		return nil, errors.Wrapf(err, "failed to mkdir %v", manager.config.Root)
-	}
-	if err := os.MkdirAll(manager.config.ExecRoot, 0700); err != nil {
-		return nil, errors.Wrapf(err, "failed to mkdir %v", manager.config.ExecRoot)
-	}
-	if err := os.MkdirAll(manager.tmpDir(), 0700); err != nil {
-		return nil, errors.Wrapf(err, "failed to mkdir %v", manager.tmpDir())
+	for _, dirName := range []string{manager.config.Root, manager.config.ExecRoot, manager.tmpDir()} {
+		if err := os.MkdirAll(dirName, 0700); err != nil {
+			return nil, errors.Wrapf(err, "failed to mkdir %v", dirName)
+		}
 	}
 
 	if err := setupRoot(manager.config.Root); err != nil {