Strange error in .gdbinit on MS-Windows

[Eli Zaretskii]

With an Emacs binary built from today's trunk, GDB barfs at startup
thusly:

  GNU gdb (GDB) 7.1
  Copyright (C) 2010 Free Software Foundation, Inc.
  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
  This is free software: you are free to change and redistribute it.
  There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
  and "show warranty" for details.
  This GDB was configured as "mingw32".
  For bug reporting instructions, please see:
  <http://www.gnu.org/software/gdb/bugs/>...
  Reading symbols from D:\gnu\bzr\emacs\test\src/./oo/i386/emacs.exe...done.
  SIGINT is used by the debugger.
  Are you sure you want to change it? (y or n) [answered Y; input not from 
termina
  l]
  Environment variable "DISPLAY" not defined.
  Environment variable "TERM" not defined.
  D:\gnu\bzr\emacs\test\src/.gdbinit:1311: Error in sourced command file:
  No struct type named Lisp_Symbol.

The same error message is displayed if I try the xsymbol command
within GDB.

This is on MS-Windows, as you see.  On GNU/Linux, I don't see this
problem.

Any ideas where to look for the reason and the fix?