[Patch] Fix libstdc++/11722

[Benjamin Kosnik]

>mainline
>--------
>22.190u 25.310s 0:47.68  99.6%    0+0k 0+0io 200pf+0w
>
>mainline + patch
>----------------
> 0.250u  0.250s 0:00.50 100.0%    0+0k 0+0io 199pf+0w

You are to be congratulated sir! This end result is great, and the patch
looks quite fine as well.

>(*) After a period of testing maybe suited for 3_4-branch too.

Please. You are already okd for this.

-benjamin