copy/copy_backward/fill/fill_n/equal rework

[Jonathan Wakely]

On 09/12/19 10:32 +0100, François Dumont wrote:
>After completing this work and running more tests I realized that the 
>declaration of algos was still not ideal.
>
>So here is another version where algos are not re-declare in 
>stl_deque.h, I rather include stl_algobase.h in deque.tcc. The problem 
>was spotted but another patch I am going to submit afterward.

OK for trunk (with a suitable ChangeLog).

Thanks for persisting with this, sorry it took so long.