[PATCH v2] emacs: add compatability functions for emacs 23

[David Bremner]

David Bremner <david at tethera.net> writes:

> The plot thickens. With this patch applied, I can generate an emacs
> segfault with
>
> 1) EMACS=emacs23 ./devel/try-emacs-mua -q
>
> 2) M-x notmuch-search <return>
>
> 3) tag:inbox <return>

OK, I managed to figure out the problem. I had byte compiled the emacs
code with emacs24, and loading that in emacs23 caused all heck to break
loose. With the byte compilation done with a matching version of emacs,
the test suite passes.

So my conclusions from all this fun:

1) since Mark went to the trouble of doing the compatiblity functions,
   we may as well get emacs23 working again.

2) It's getting hard to debug emacs23 problems, and developer time is
   scarce, so at the same time, deprecate emacs23 support, so e.g. after
   the next major release we can just drop it.

3) With the caveat that we plan to drop the compat functions, I leave it
   to mark's judgement whether it's worth putting them in a seperate
   file, or just adding the FSF copyright to the top of the file.