[patch] fix libstdc++/55631

[Jonathan Wakely]

On 11 December 2012 22:31, Jonathan Wakely wrote:
>         PR libstdc++/55631
>         * include/ext/alloc_traits.h: Include missing header.
>         * include/ext/pointer.h: Likewise.
>         * include/ext/string_conversions.h: Require C++11.
>         * libsupc++/initializer_list: Reindent.
>
> Tested x86_64-linux, committed to trunk.

Also committed to the 4.7 branch, the <ext/pointer.h> error is a
regression from 4.6