A-23 and ABI header file

[Jim Dehnert]

>From Matt's meeting writeup:

> Naming issue: we decided to put all of our type_info subclasses
> in namespace abi, not namespace std.  This means, of course,
> that they can't go in any of the standard headers.  Rather than
> inventing multiple header names, we would like to put everything
> (unwinding longjmp, type_info subclasses, etc.) into one quasi-
> standard header.  We propose the name <ia64cxxabi>.  Everything
> in that header will be in namespace abi.

We previously decided on cxxabi.h for the header, in conjunction
with D-9 (longjmp).  Aside from the ".h", which I don't care about,
I prefer not including "ia64" because I have quixotic notions about the
possibility of this ABI spreading elsewhere, and don't think source
code ought to need to change in such cases.

Jim

-		Jim Dehnert  x3-4272