C++ header compatibility patches

[Benjamin Kosnik]

Recently, as part of a discussion about making libstdc++ play nice with
QNX 6.1 and higher, I investigated ways of adding conformant C++
wrappers to newlib.

It's actually surprisingly easy. I posted a patch here:
http://gcc.gnu.org/ml/libstdc++/2002-06/msg00171.html

There remains some C++ work, so I've added bits in _ansi.h to turn off
the namespace capability. It should be off for now, and then perhaps
sometime in the near future this bit could be flipped.

Could somebody review this please?

thanks,
benjamin