Crash when displaying gif images

[Peter Fales]

I'm seeing a repeatable crash with 6.6.7-10 and 6.6.8-5 (possibly earlier,
but not tested) running on Linux.

To reproduce, use "display" to show a gif image, then right-click and
select next. This consistently causes a crash, but only with gif
files. It doesn't happen with .png or .jpg

The stack trace from 6.6.7-10 is below (but I suspect the real memory
error is somewhere else - such as the gif code - and is only showing up later)

(gdb) bt
#0 0x42074d81 in malloc_consolidate () from /lib/tls/libc.so.6
#1 0x42074c68 in _int_free () from /lib/tls/libc.so.6
#2 0x42073908 in free () from /lib/tls/libc.so.6
#3 0x40a956ab in _XF86BigfontFreeFontMetrics ()
from /usr/X11R6/lib/libX11.so.6
#4 0x40a949d8 in XFreeFont () from /usr/X11R6/lib/libX11.so.6
#5 0x401dd87c in DestroyXResources () at magick/xwindow.c:377
#6 0x401dff44 in XComponentTerminus () at magick/xwindow.c:1649
#7 0x4013e7d6 in MagickCoreTerminus () at magick/magick.c:1371
#8 0x08048859 in main (argc=2, argv=0xbffff714) at utilities/display.c:111
(gdb)