Simplify some code with Boost.Operators

Change-Id: Ic873bcbaf6be00d5c35601cfc8090df534d815ee
diff --git a/daemon/rib/readvertise/readvertised-route.hpp b/daemon/rib/readvertise/readvertised-route.hpp
index a57fe70..bc2d8c1 100644
--- a/daemon/rib/readvertise/readvertised-route.hpp
+++ b/daemon/rib/readvertise/readvertised-route.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022,  Regents of the University of California,
+ * Copyright (c) 2014-2023,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -33,7 +33,8 @@
 
 namespace nfd::rib {
 
-/** \brief State of a readvertised route.
+/**
+ * \brief State of a readvertised route.
  */
 class ReadvertisedRoute : noncopyable
 {
@@ -41,25 +42,23 @@
   explicit
   ReadvertisedRoute(const Name& prefix)
     : prefix(prefix)
-    , nRibRoutes(0)
-    , retryDelay(0)
   {
   }
 
+  friend bool
+  operator<(const ReadvertisedRoute& lhs, const ReadvertisedRoute& rhs)
+  {
+    return lhs.prefix < rhs.prefix;
+  }
+
 public:
   Name prefix; ///< readvertised prefix
   mutable ndn::security::SigningInfo signer; ///< signer for commands
-  mutable size_t nRibRoutes; ///< number of RIB routes that cause the readvertisement
-  mutable time::milliseconds retryDelay; ///< retry interval (not used for refresh)
+  mutable size_t nRibRoutes = 0; ///< number of RIB routes that cause the readvertisement
+  mutable time::milliseconds retryDelay = 0_ms; ///< retry interval (not used for refresh)
   mutable scheduler::ScopedEventId retryEvt; ///< retry or refresh event
 };
 
-inline bool
-operator<(const ReadvertisedRoute& lhs, const ReadvertisedRoute& rhs)
-{
-  return lhs.prefix < rhs.prefix;
-}
-
 using ReadvertisedRouteContainer = std::set<ReadvertisedRoute>;
 
 } // namespace nfd::rib