Add c++11 effective target to tests for C++11 features

	* testsuite/20_util/tuple/67844.cc: Require c++11 effective target.
	* testsuite/20_util/tuple/cons/nested_tuple_construct.cc: Likewise.
	* testsuite/27_io/rvalue_streams.cc: Likewise.

From-SVN: r239545

libstdc++-v3/ChangeLog

 2016-08-17  Jonathan Wakely  <jwakely@redhat.com>
 
+	* testsuite/20_util/tuple/67844.cc: Require c++11 effective target.
+	* testsuite/20_util/tuple/cons/nested_tuple_construct.cc: Likewise.
+	* testsuite/27_io/rvalue_streams.cc: Likewise.
+
 	* testsuite/26_numerics/complex/literals/types.cc: Add comment.
 
 	* testsuite/21_strings/basic_string_view/operations/rfind/char/2.cc:

libstdc++-v3/testsuite/20_util/tuple/67844.cc

-// { dg-do compile }
+// { dg-do compile { target c++11 } }
 
 // Copyright (C) 2015-2016 Free Software Foundation, Inc.
 //

libstdc++-v3/testsuite/20_util/tuple/cons/nested_tuple_construct.cc

+// { dg-do run { target c++11 } }
+
 // Copyright (C) 2015-2016 Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free

libstdc++-v3/testsuite/27_io/rvalue_streams.cc

@@ -15,7 +15,7 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-// { dg-do run }
+// { dg-do run { target c++11 } }
 
 #include <sstream>
 #include <string>