Make string_view operations involving CharT* *not* noexcept and consistent beween string_view and string_view.tcc.

[Jonathan Wakely]

On 29 March 2014 21:18, Marc Glisse wrote:
> I notice that the default constructor and basic_string_view(nullptr,n) have
> _M_str point to a special array. What would break with using 0?


IIRC in Issaquah we changed the string_view spec to remove the
guarantee that data() never returns nullptr, so the special array is
no longer needed.