[v3] c++0x common_type patch

[Paolo Carlini]

Hi,

> Sorry Paolo, my usual coding style is nearly completely different
> so my eyes aren't trained for things things yet.

No problem, but please help... ideally patches should be applicable as-they-are to be accepted.

 Speaking of
> formatting, 
> http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01apas03.html
> in both IE and FF show no indentation in any of the examples.

Yeah, that document is very, very, old, only recently moved to the new doc framework. I think it needs some work... volunteering?!? ;)

Thanks,
Paolo.

PS: Normally we svn diff from *inside* libstdc++...