support for autoconf 2.13

[Bruno Haible]

Hi,

This patch fixes a huge expansion of the word 'symbols' that occurs within
comments. Only needed with autoconf <= 2.13.


2001-06-08  Bruno Haible  <address@hidden>

        * libtool.m4: Undefine 'symbols'.

*** libtool-1.4.3/libtool.m4    2002-10-23 02:45:04.000000000 +0200
--- libtool.m4  2003-02-16 14:01:42.000000000 +0100
***************
*** 22,27 ****
--- 22,30 ----
  ## configuration script generated by Autoconf, you may include it under
  ## the same distribution terms that you use for the rest of that program.
  
+ # Avoid expanding a built-in token inside comments with autoconf-2.13.
+ builtin([undefine],[symbols])
+ 
  # serial 46 AC_PROG_LIBTOOL
  
  AC_DEFUN([AC_PROG_LIBTOOL],