[2432] Use prefix operator++

src/lib/dns/rrset_collection.h

@@ -142,7 +142,7 @@ protected:
 
         virtual IterPtr getNext() {
             CollectionMap::iterator it = iter_;
-            it++;
+            ++it;
             return (RRsetCollectionBase::IterPtr(new DnsIter(it)));
         }
 

src/lib/dns/tests/rrset_collection_unittest.cc

@@ -201,7 +201,7 @@ protected:
 
         virtual IterPtr getNext() {
             MyCollection::iterator it = iter_;
-            it++;
+            ++it;
             return (RRsetCollectionBase::IterPtr(new MyIter(it)));
         }