diff --git a/cf/check-lex.m4 b/cf/check-lex.m4
new file mode 100644
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--- /dev/null
+++ b/cf/check-lex.m4
@@ -0,0 +1,149 @@
+#
+# XXX remove this when we get autoconf 2.61
+#
+
+
+# This file is part of Autoconf.                       -*- Autoconf -*-
+# Checking for programs.
+
+# Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
+# 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301, USA.
+
+# As a special exception, the Free Software Foundation gives unlimited
+# permission to copy, distribute and modify the configure scripts that
+# are the output of Autoconf.  You need not follow the terms of the GNU
+# General Public License when using or distributing such scripts, even
+# though portions of the text of Autoconf appear in them.  The GNU
+# General Public License (GPL) does govern all other use of the material
+# that constitutes the Autoconf program.
+#
+# Certain portions of the Autoconf source text are designed to be copied
+# (in certain cases, depending on the input) into the output of
+# Autoconf.  We call these the "data" portions.  The rest of the Autoconf
+# source text consists of comments plus executable code that decides which
+# of the data portions to output in any given case.  We call these
+# comments and executable code the "non-data" portions.  Autoconf never
+# copies any of the non-data portions into its output.
+#
+# This special exception to the GPL applies to versions of Autoconf
+# released by the Free Software Foundation.  When you make and
+# distribute a modified version of Autoconf, you may extend this special
+# exception to the GPL to apply to your modified version as well, *unless*
+# your modified version has the potential to copy into its output some
+# of the text that was the non-data portion of the version that you started
+# with.  (In other words, unless your change moves or copies text from
+# the non-data portions to the data portions.)  If your modification has
+# such potential, you must delete any notice of this special exception
+# to the GPL from your modified version.
+#
+# Written by David MacKenzie, with help from
+# Franc,ois Pinard, Karl Berry, Richard Pixley, Ian Lance Taylor,
+# Roland McGrath, Noah Friedman, david d zuhn, and many others.
+
+
+# AC_PROG_LEX
+# -----------
+# Look for flex or lex.  Set its associated library to LEXLIB.
+# Check if lex declares yytext as a char * by default, not a char[].
+AN_MAKEVAR([LEX],  [AC_PROG_LEX])
+AN_PROGRAM([lex],  [AC_PROG_LEX])
+AN_PROGRAM([flex], [AC_PROG_LEX])
+AC_DEFUN_ONCE([AC_PROG_LEX],
+[AC_CHECK_PROGS(LEX, flex lex, :)
+if test "x$LEX" != "x:"; then
+  _AC_PROG_LEX_YYTEXT_DECL
+fi])
+
+
+# _AC_PROG_LEX_YYTEXT_DECL
+# ------------------------
+# Check for the Lex output root, the Lex library, and whether Lex
+# declares yytext as a char * by default.
+m4_define([_AC_PROG_LEX_YYTEXT_DECL],
+[cat >conftest.l <<_ACEOF[
+%%
+a { ECHO; }
+b { REJECT; }
+c { yymore (); }
+d { yyless (1); }
+e { yyless (input () != 0); }
+f { unput (yytext[0]); }
+. { BEGIN INITIAL; }
+%%
+#ifdef YYTEXT_POINTER
+extern char *yytext;
+#endif
+int
+main (void)
+{
+  return ! yylex () + ! yywrap ();
+}
+]_ACEOF
+_AC_DO_VAR(LEX conftest.l)
+AC_CACHE_CHECK([lex output file root], [ac_cv_prog_lex_root], [
+if test -f lex.yy.c; then
+  ac_cv_prog_lex_root=lex.yy
+elif test -f lexyy.c; then
+  ac_cv_prog_lex_root=lexyy
+else
+  AC_MSG_ERROR([cannot find output from $LEX; giving up])
+fi])
+AC_SUBST([LEX_OUTPUT_ROOT], [$ac_cv_prog_lex_root])dnl
+
+if test -z "${LEXLIB+set}"; then
+  AC_CACHE_CHECK([lex library], [ac_cv_lib_lex], [
+    ac_save_LIBS=$LIBS
+    ac_cv_lib_lex='none needed'
+    for ac_lib in '' -lfl -ll; do
+      LIBS="$ac_lib $ac_save_LIBS"
+      AC_LINK_IFELSE([`cat $LEX_OUTPUT_ROOT.c`], [ac_cv_lib_lex=$ac_lib])
+      test "$ac_cv_lib_lex" != 'none needed' && break
+    done
+    LIBS=$ac_save_LIBS
+  ])
+  test "$ac_cv_lib_lex" != 'none needed' && LEXLIB=$ac_cv_lib_lex
+fi
+AC_SUBST(LEXLIB)
+
+AC_CACHE_CHECK(whether yytext is a pointer, ac_cv_prog_lex_yytext_pointer,
+[# POSIX says lex can declare yytext either as a pointer or an array; the
+# default is implementation-dependent.  Figure out which it is, since
+# not all implementations provide the %pointer and %array declarations.
+ac_cv_prog_lex_yytext_pointer=no
+ac_save_LIBS=$LIBS
+LIBS="$LEXLIB $ac_save_LIBS"
+AC_LINK_IFELSE(
+  [#define YYTEXT_POINTER 1
+`cat $LEX_OUTPUT_ROOT.c`],
+  [ac_cv_prog_lex_yytext_pointer=yes])
+LIBS=$ac_save_LIBS
+])
+dnl
+if test $ac_cv_prog_lex_yytext_pointer = yes; then
+  AC_DEFINE(YYTEXT_POINTER, 1,
+	    [Define to 1 if `lex' declares `yytext' as a `char *' by default,
+	     not a `char[]'.])
+fi
+rm -f conftest.l $LEX_OUTPUT_ROOT.c
+])# _AC_PROG_LEX_YYTEXT_DECL
+
+
+# Require AC_PROG_LEX in case some people were just calling this macro.
+AU_DEFUN([AC_DECL_YYTEXT],  [AC_PROG_LEX])
+
+