RFA: abstract C++ ABI dependencies

[Jim Blandy]

Daniel Berlin <dan@www.cgsoftware.com> writes:
> > > *NONE* of these files initialize the rtti_type field within the
> > > cp_abi_ops structure; they all let it default to 0.
> 
> This is normal, actually.
> gnuv-2's rtti type is broken
> Until the HP stuff is verified to work, it  avoids problems.

Right, but I'm trying to post a patch which changes the behavior of
GDB as little as possible.  Further changes, even good ones, should be
posted as separate patches.