[patch] Improving shared_ptr for C++0x

[Paolo Carlini]

Jonathan Wakely wrote:
> I can't test it on cygwin or darwin but this patch should fix it.
> Shall I commit this?
>   
Ah, I see, those two targets are listed among the dg-do run targets but
-std=c++0x is missing.

The patch seems obviously correct, then. Please go ahead.

Thanks,
Paolo.