C++ and dwarfcmp

[Roland McGrath <roland at redhat dot com>]

Hi!  Happy New Year!

I got started a bit over xmas and now I've snuck up on the first milestone
in DwarfTasks.  I'll post a formal status report in the morning.
But I wanted to mention the technical stuff.

First is the new branch:
	roland/fixes-for-c++
This has changes to the existing C code that I think can be merged in soon.
This is so far just one little thing I noticed while doing the C++ stuff.
It's either a bug or a change in the error case behavior, depending how you
look at it.  I think it's right enough for C libdw too, and without it I'd
have to do some bad workaround in the C++ wrapper.  I'll put other nits of
the same ilk here as I come across them.

Forking from that is the new branch:
	roland/dwarf-c++
This contains new C++ code and dwarfcmp.
This is highly prototypey, unfinished, unclean stuff.
The placement of files and code will change before it's real.

The C++ header is thoroughly unreadable.  It will get cleaner and commented
before it's firm, but it will still be unreadable (welcome to C++).  
The hope is that C++ code that just uses the interfaces will be relatively
easy to read though.

The code works enough for dwarfcmp to run, and it succeeded on three small
cases (both comparing files to themselves and comparing different files).
It is roughly up to the 1.2 milestone on DwarfTasks.  This week I'll do the
exhaustive tests for "dwarfcmp -q file file" and fix bugs.

It's not finished or used yet, but I also did the basic sketch of the code
for the 2.5 milestone (skeleton writable interface).  I hope to get that
prototype finished this week too.

When any of this is slightly cleaned up, I'll turn this into a shared
branch for the new DWARF work in general, and we can merge dwarflint there.

My next other task will be writing up the missing DwarfValues page about
the thinking for attr values, the missing heart of the C++ interface.
I should get some words down on that this week, if not any actual work.


Thanks,
Roland