helper: Add LFID route calculation

Loop-Free In-port Dependent (LFID) route calculation provides a set of loop-free paths.

Basically porting the existing code from https://github.com/schneiderklaus/ndnSIM-routing

Refs: #4985
Change-Id: I1ab25e729851cf2233c3b99be715ba0159cca0c7
diff --git a/helper/ndn-global-routing-helper.hpp b/helper/ndn-global-routing-helper.hpp
index b405838..d14b2fe 100644
--- a/helper/ndn-global-routing-helper.hpp
+++ b/helper/ndn-global-routing-helper.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2011-2015  Regents of the University of California.
+ * Copyright (c) 2011-2019  Regents of the University of California.
  *
  * This file is part of ndnSIM. See AUTHORS for complete list of ndnSIM authors and
  * contributors.
@@ -101,6 +101,19 @@
   CalculateRoutes();
 
   /**
+   * @brief Calculates a set of loop-free multipath routes.
+   *
+   * For full description please see tech tech report "Hop-by-Hop Multipath Routing:
+   * Choosing the Right Nexthop Set" and the associated Github repository:
+   *
+   * https://github.com/schneiderklaus/ndnSIM-routing
+   *
+   * @sa https://named-data.net/publications/techreports/mp_routing_tech_report/
+   */
+  static void
+  CalculateLfidRoutes();
+
+  /**
    * @brief Calculate all possible next-hop independent alternative routes
    *
    * Refer to the implementation for more details.