RFC: C/C++ preprocessor macro support for GDB

[Andrew Cagney]

Hmm,

I get the feeling that we're going to end up with:

	gcc/libcpp
and 
src/libcpp

Fun!  Are there intermediate steps to this goal?  For instance, resolve 
the directory name and the interfaces GDB will need.  That way some of 
the GDB side can make progress, even if it is initially calling stubbed 
or ``broken'' libcpp code.

enjoy,
Andrew