[Patch] Fix libstdc++/12438

[Paolo Carlini]

Benjamin Kosnik wrote:

>>The below is the updated patch (testcase checked with/without the fix)
>>which I'd like to commit soon.
>>    
>>
>These look great Paolo. Can you move this work over to the gcc-3_3-branch?
>
Hi Banjamin!
No more than a few hours ago I was thinking: "perhaps some of these 
patches could be safely moved to 3_3... I have to ask the list!"

So... Which ones, Benjamin?

The whole thread safety triple? For 12352, 12352 cont and 12438?

Probably 11400 and 12296 are safe too.

Paolo.