pass by reference, not an object, to avoid unnecessary copy

git-svn-id: svn://bind10.isc.org/svn/bind10/trunk@1029 e5f2f494-b856-4b98-b285-d166d9295462

src/lib/dns/cpp/rrsetlist.h

@@ -82,7 +82,7 @@ public:
                             const RRClass& rrclass = RRClass::IN());
     RRsetPtr findRRset(ConstRRsetPtr rrsetptr);
 
-    RRsetPtr operator[](RRType t) { return (this->findRRset(t)); }
+    RRsetPtr operator[](const RRType& t) { return (this->findRRset(t)); }
 
     typedef RRsetListIterator<std::vector<RRsetPtr>::iterator,
                               RRsetPtr*,