security: Convert ValidatorConfig to ValidationPolicyConfig

The security API also provides a convenience ValidatorConfig helper.

Change-Id: Ic86dec4904b917361cb4740204de4b6710d2a386
Refs: #3920
diff --git a/src/security/v2/validation-policy.hpp b/src/security/v2/validation-policy.hpp
index 351ffed..d7a261b 100644
--- a/src/security/v2/validation-policy.hpp
+++ b/src/security/v2/validation-policy.hpp
@@ -1,5 +1,5 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
+/*
  * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
@@ -65,6 +65,20 @@
   void
   setInnerPolicy(unique_ptr<ValidationPolicy> innerPolicy);
 
+  /**
+   * @brief Check if inner policy is set
+   */
+  bool
+  hasInnerPolicy() const
+  {
+    return m_innerPolicy != nullptr;
+  }
+
+  /**
+   * @brief Return the inner policy
+   *
+   * If the inner policy was not set, behavior is undefined.
+   */
   ValidationPolicy&
   getInnerPolicy();