QDuplicateTracker: add rvalue overload

We have at least one user that only ever passes rvalues.

Change-Id: I3f190b8d074e40a23c52e791635c9a1c45ba00ab
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

src/corelib/tools/qduplicatetracker_p.h

@@ -84,6 +84,18 @@ public:
         set.insert(s);
         const int n = set.size();
         inserted = qExchange(setSize, n) != n;
+#endif
+        return !inserted;
+    }
+    Q_REQUIRED_RESULT bool hasSeen(T &&s)
+    {
+        bool inserted;
+#ifdef __cpp_lib_memory_resource
+        inserted = set.insert(std::move(s)).second;
+#else
+        set.insert(std::move(s));
+        const int n = set.size();
+        inserted = qExchange(setSize, n) != n;
 #endif
         return !inserted;
     }