PATCH RFA: Permit backward/hash_map with -Wdeprecated

[Paolo Carlini]

Hi,
>
> With the patch applied, the warning will continue to occur by default
> just as it does today.

I see now, patch is ok, thanks.

> I of course understand the manpower argument but I don't think it
> applies here.  Nobody is expecting the libstdc++ maintainers to fix
> bugs in this old code.

I agree, but I said that only because I was afraid we wouldn't warn  
anymore by default, thus not discouraging people to use these classes  
for new code.

Paolo