Some shadow fixes.

[Benjamin Kosnik]

Nathan, can you summarize the state of this patch? It seems to me that all 
the problem functions should just be declared "extern 'c'" and then they 
are good for both std:: and ::

Right?

Can the  patch be revised to take this into account, and to deal with the 
change from _C_Swamp -> _C_Legacy?


>Note, though, that the C++ standard doesn't include the C99 extensions,
>so any such have to be guarded with #ifdef __USE_C9X.

This is an internal contradiction to the standard. It's clearly the 
intention of C++ to be a superset of C, including C9X. Let's deal with 
the C9X issues the same way we deal with depricated code 
(_GLIBCPP_DEPRICATED) or issues that have been resolved after the 
standard was aproved (_GLIBCPP_RESOLVE_LIB_DEFECTS). 

Ie, in bits/c++config.h

# _GLIBCPP_USE_C9X 1

-benjamin