[libstdc++-v3][C++14] Implement N3654 - Quoted Strings

[Jonathan Wakely]

On 8 June 2013 04:44, Ed Smith-Rowland wrote:
>
> OK, I added a static_assert to check that _String is only reference or
> pointer.
> I also added a tests that check the case where _String is 'const
> basic_string<>&'.
>
> Built and tested on x86_64-linux.
>
> OK?

This is OK to commit to trunk. Thanks, Ed!