constexpr for tr2/bool_set.

[Ed Smith-Rowland]

-------------- next part --------------
Index: include/tr2/bool_set
===================================================================
--- include/tr2/bool_set	(revision 188848)
+++ include/tr2/bool_set	(working copy)
@@ -1,6 +1,6 @@
 // TR2 <bool_set> -*- C++ -*-
 
-// Copyright (C) 2009, 2011 Free Software Foundation, Inc.
+// Copyright (C) 2009, 2011, 2012 Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
@@ -56,10 +56,10 @@
   public:
 
     ///  Default constructor.
-    bool_set() : _M_b(_S_false) { }
+    constexpr bool_set() : _M_b(_S_false) { }
 
     ///  Constructor from bool.
-    bool_set(bool __t) : _M_b(_Bool_set_val(__t)) { }
+    constexpr bool_set(bool __t) : _M_b(_Bool_set_val(__t)) { }
 
     // I'm not sure about this.
     bool contains(bool_set __b) const