bug#12402: 24.2.50; Crash switching to ibuffer

[Eli Zaretskii]

> Date: Mon, 10 Sep 2012 15:41:26 +0100
> From: Andy Moreton <amoreton@solarflare.com>
> 
> During normal editing I tried to switch to the ibuffer buffer, and emacs
> aborted (backtrace below). Built from a clean bootstrap of r109965.
> 
> In GNU Emacs 24.2.50.1 (i386-mingw-nt5.1.2600)
>   of 2012-09-10 on AJM-DESKTOP
> Bzr revision: 109965 cyd@gnu.org-20120910032510-vrblnwlfnsb0cx3s
> Windowing system distributor `Microsoft Corp.', version 5.1.2600
> Configured using:
>   `configure --with-gcc (4.6) --no-opt --enable-checking --cflags
>   -IC:/emacs/devel/libxml2-2.7.8/include/libxml2
>   -IC:/emacs/devel/giflib-4.1.4-1/include
>   -IC:/emacs/devel/jpeg-6b-4/include
>   -IC:/emacs/devel/tiff-3.8.2-1/include
>   -IC:/emacs/devel/libpng-1.4.3-1/include
>   -IC:/emacs/devel/xpm-3.5.1-1/include
>   -IC:/emacs/devel/xpm-3.5.1-1/src/xpm/3.5.1/libXpm-3.5.1-src/lib
>   -IC:/emacs/devel/zlib-1.2.5-2/include'
> 
> Backtrace with "bt full":
> 
> #0  0x7c90120f in ntdll!DbgUiConnectToDbg () from C:\WINDOWS\system32\ntdll=
> .dll
> No symbol table info available.
> #1  0x01153186 in emacs_abort () at w32fns.c:7215
>          button = 0x6
> #2  0x012e632c in relinquish () at ralloc.c:333
>          h = 0x0
>          excess = 0x3d0d80

I installed a change that might eliminate this problem, as trunk
revision 110430.  Please test.