bug#4375: 23.1.50; can't kill killed gud buffer

> Emacs 23.1 is always an option for those using older GDB releases.

Rather you mean "using gud-gdb is always an option for those using older
GDB releases" (we're talking about what to do for Emacs-23.2, so we
take for granted that the user will be using Emacs-23.2).
That might be good enough (I personally always end up using gud-gdb
since I've always found M-x gdb to be somewhat unreliable).

> properly to GDB/MI is not an easy thing to do and I want to focus on that
> rather than on compatibility with old versions of GDB.

Preserving the gdb-ui.el code should be doable without any interference
with gdb-mi.el.  The code they share via gud.el is pretty small.

>> BTW, as you probably already know, I really think that M-x gdb should Do
>> the Right Thing, whether gdb is run with --annotate=2, --annotate=3,
>> or -i=mi.  I.e. it should wait to see GDB's output and then decide based
>> on that output whether to use gdb-mi.el or gdb-ui.el or just gud.el.
> We used to do that with "--fullname" and "--annotate=3" but that caused
> problems when execution was started in the users .gdbinit file.  The two
> options are now invoked with separate functions (M-x gud-gdb and M-x gdb).

I know, but I still think this is a temporary workaround.  We should
document it well in some comments to make sure someone who wants to
attack the problem doesn't waste time going through the same problems
agains.


        Stefan