Merge pull request dogecoin#3490 from patricklodder/1.15.0-const-comparator-operator

net: make IteratorComparator's operator const

Author: chromatic

src/net_processing.cpp

@@ -43,7 +43,7 @@ std::atomic<int64_t> nTimeBestReceived(0); // Used only to inform the wallet of
 struct IteratorComparator
 {
     template<typename I>
-    bool operator()(const I& a, const I& b)
+    bool operator()(const I& a, const I& b) const
     {
         return &(*a) < &(*b);
     }