[v3] use noexcept in pointer_traits

[Jonathan Wakely]

I missed the "noexcept" qualifier off this function when I added it recently.

2011-06-14  Jonathan Wakely  <jwakely....@gmail.com>

        * include/bits/ptr_traits.h (pointer_traits<T*>::pointer_to): Use
        noexcept.

Tested x86_64-linux and committed to trunk

Index: include/bits/ptr_traits.h
===================================================================
--- include/bits/ptr_traits.h   (revision 175056)
+++ include/bits/ptr_traits.h   (working copy)
@@ -211,7 +211,7 @@
        *  @return @c addressof(r)
       */
       static pointer
-      pointer_to(typename __ptrtr_not_void<element_type>::__type& __r)
+      pointer_to(typename __ptrtr_not_void<element_type>::__type& __r) noexcept
       { return std::addressof(__r); }
     };