"Last minute" fix for libstdc++/20806

[Paolo Carlini]

Benjamin Kosnik wrote:

>>the below is what I have regtested, to be safe, on x86-linux. This
>>approach is reported to fix the problem on mingw32. Generally, I
>>consider the patch very safe on anything != mingw32 and would take the
>>risk of applying it very close to the release of 4.0, if the mingw32
>>maintainer approves its specific bits.
>>    
>>
>Me too.
>
>I would just go ahead and apply this: it looks fine. It seems pretty low-risk to me.
>
>Of course, I can apply this for you next week if it's desired.
>  
>
Ok, agreed. I will just wait 'til this evening italian time, in case of
comments.

In case any problem surfaces during next week, when I will be in
Lillehammer, will be totally up to you what to do with this issue.
Thanks in advance, anyway.

Paolo.