[patch] Improving shared_ptr for C++0x

[Paolo Carlini]

Hi Jonathan,

I have a small comment and a much more substantive one: the first one is 
that, as a general rule, we try not to have #include in the tr1_impl 
headers. The second one is that I'm rather concerned, at this stage of 
the development process, that the changes touching both the 
_GLIBCXX_INCLUDE_AS_TR1 and _GLIBCXX_INCLUDE_AS_CXX0X versions of code 
(basically the first part of your patch) can somehow, unadvertently 
damage the TR1 implementation which, by now, is rather stable. Would you 
consider splitting completely the first part of the implementation to 
/std and /tr1 (the second part in /tr1_impl, of course), similarly to 
what we are doing for type_traits? I'm sure there will be some 
redundancy but we'll be also much safer. In that case you can consider 
your changes morally pre-approved (just let me have a look ;)

Thanks,
Paolo.