Fix typename in forward (#6183)

This was noted by another Googler.

common/map_test.cpp

@@ -77,7 +77,7 @@ auto MakeKeyValues(ValueCB value_cb, RangeT&& range, RangeTs&&... ranges)
     }
   };
   add_range(std::forward<RangeT>(range));
-  (add_range(std::forward<RangeT>(ranges)), ...);
+  (add_range(std::forward<RangeTs>(ranges)), ...);
 
   return elements;
 }

common/set_test.cpp

@@ -51,7 +51,7 @@ auto MakeElements(RangeT&& range, RangeTs&&... ranges) {
     }
   };
   add_range(std::forward<RangeT>(range));
-  (add_range(std::forward<RangeT>(ranges)), ...);
+  (add_range(std::forward<RangeTs>(ranges)), ...);
 
   return elements;
 }