bug#12989: 24.3.50; buffer-file-type is not buffer-local

[Eli Zaretskii]

> Date: Sun, 25 Nov 2012 18:50:05 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 12989@debbugs.gnu.org
> 
> I will work on removing the variable entirely from the sources, though
> I guess it's too late for 24.3.  So I will do it on the trunk.

Now done (revision 111709 on the trunk).

There are still references to find-buffer-file-type (which no longer
exists as of the above revision) in tramp-sh.el.  The code there is
commented as being for XEmacs only, and I don't really understand what
is it trying to accomplish.  Michael, could you please take a look?
Ideally, we should delete all that stuff, unless it breaks XEmacs.

A question for Stefan: should I also remove these from subr.el:

  (make-obsolete-variable 'default-buffer-file-type 'buffer-file-type "23.2")
  (defvar-local buffer-file-type nil
    "Non-nil if the visited file is a binary file.
  This variable is meaningful on MS-DOG and MS-Windows.
  On those systems, it is automatically local in every buffer.
  On other systems, this variable is normally always nil.

  WARNING: This variable is obsolete and will disappear Real Soon Now.
  Don't use it!")

I thought I'd leave them in case some non-bundled code uses them.  But
maybe this is not needed.