[Patch] First bits of the algo merge

[Paolo Carlini]

Hi Howard,

and, first, thanks a lot for the interesting technical discussion!

[snip]

> If we want to accommodate those customers, a simple fix is:
>
> +      return std::mismatch(__first1, __last1, __first2,
> +               __gnu_cxx::__ops::equal_to<value_type1, value_type2>());
>      }
>
>
> +  template<typename _Lhs, typename _Rhs>
> +  struct equal_to
> +  {
> +      bool
> +      operator()(const _Lhs& __lhs, const _Rhs& __rhs) const
> +      { return __lhs == __rhs; }
> +  };

assuming nobody disagree (well, Chris, in particular), I will adjust
things as part of the merge, everywhere.

One thing, useful also for people in order to better understand those
delicate technical points: can I ask you a simple testcase that
currently would fail (in v7-branch)? Then, at some point we can also add it.

Thanks again,
Paolo.