[v3] Add / use _GLIBCXX_MOVE in algorithm

[Paolo Carlini]

Hi,

>As I understand this, analogous effort has still to be done for the sort
>routines, right? (That's not an accusation).
>
Thanks, I feel relieved ;)

> Is this the reason for the
>corresponding test cases still being UNSUPPORTED?
>  
>
Of course. In general, I never do this kind of delicate changes all at 
once. At the moment, I'm finishing std::move and std::move_backward, 
which are necessary in many places. In the v7 branch we have something 
ready also for (some) sort routines, but if you have something well 
tested (and your Copyright assignment is in place, sorry I have no 
idea), feel free to post it!

Thanks,
Paolo.