bug#1295: Segfault with `M-- M-r' when `scroll-margin' > 0

[Richard M. Stallman]

     > 2008-11-03  Chong Yidong  <cyd@stupidchicken.com>
     >
     >  * term/x-win.el (x-initialize-window-system): Call
     >  x-wm-set-size-hint after initialization.
     >
     > Could you see whether the problem is fixed for you?

    Still crashes here.  But just before crashing, display of the center line
    of the window gets garbled now.  So it appears related to these size hints.

If we think that a bug in Lisp code causes a crash,
we should think about whether there's a bug in the C code
which it is triggering.