[c++0x] shared_ptr get() and use_count() inconsistency

[Peter Dimov]

Rodolfo Lima:

> The current standard draft says that use_count() should return 0 if the 
> shared_ptr is empty, and get() should return NULL if the shared_ptr is 
> also empty.

http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-active.html#711