nlsr: refactor AdjacencyList to use iterators instead of bare ptrs

Change-Id: I42225ee63c3d64eb80e58bc51c8d1afd20dd2ce2
refs: #4068
diff --git a/src/adjacency-list.hpp b/src/adjacency-list.hpp
index 4cf816e..c9553de 100644
--- a/src/adjacency-list.hpp
+++ b/src/adjacency-list.hpp
@@ -139,10 +139,10 @@
     }
   }
 
-  Adjacent*
+  AdjacencyList::iterator
   findAdjacent(const ndn::Name& adjName);
 
-  Adjacent*
+  AdjacencyList::iterator
   findAdjacent(uint64_t faceId);
 
   uint64_t
@@ -173,4 +173,4 @@
 };
 
 } // namespace nlsr
-#endif //NLSR_ADJACENCY_LIST_HPP
+#endif // NLSR_ADJACENCY_LIST_HPP