bug#14274: 24.3; disable undo for *Buffer List*

[Stefan Monnier]

> After my Emacs has been running for a while, I get warnings like this:
> ----
> Warning (undo): Buffer `*Buffer List*' undo info was 12075571 bytes long.
> The undo info was discarded because it exceeded `undo-outer-limit'.

Indeed, this buffer is updated as side-effect of various commands that
happen in other buffers, so we fail to regularly call undo-boundary
(which is automatically called at the end of each command, but only in
the currently selected buffer).

Disabling undo sounds like a good fix.  I even applied it to the parent
major mode so it will also apply to process-list and a few more.


        Stefan