This is a minimal patch that does not keep indentation consistent in tcl.m4
Updating indentation would make the patch much bigger and less readable.

Signed-off-by: Gilles Espinasse <g.esp@free.fr>

Index: INSTALL
===================================================================
RCS file: /cvsroot/expect/expect/INSTALL,v
retrieving revision 5.30
diff -u -r5.30 INSTALL
--- INSTALL	21 Jun 1999 18:41:41 -0000	5.30
+++ INSTALL	30 May 2009 11:51:21 -0000
@@ -152,6 +152,7 @@
 
 	--with-tk=...		Specifies the directory containing Tk's
 				configure file (tkConfig.sh).
+				--with-tk=no disable Tk usage in expect
 
 	--with-tkinclude=...	Specifies the directory containing Tk's
 				private include files (such as tkInt.h)
Index: Makefile.in
===================================================================
RCS file: /cvsroot/expect/expect/Makefile.in,v
retrieving revision 5.45
diff -u -r5.45 Makefile.in
--- Makefile.in	3 Oct 2008 17:05:14 -0000	5.45
+++ Makefile.in	30 May 2009 11:51:21 -0000
@@ -103,7 +103,11 @@
 PKG_STUB_LIB_FILE = @PKG_STUB_LIB_FILE@
 
 lib_BINARIES	= $(PKG_LIB_FILE)
-bin_BINARIES	= expect expectk
+bin_BINARIES	= expect
+ifneq ($(TK_BIN_DIR),)
+  bin_BINARIES	+= expectk
+endif
+
 BINARIES	= $(lib_BINARIES) $(bin_BINARIES)
 
 SHELL		= @SHELL@
Index: tclconfig/tcl.m4
===================================================================
RCS file: /cvsroot/expect/expect/tclconfig/tcl.m4,v
retrieving revision 1.3
diff -u -r1.3 tcl.m4
--- tclconfig/tcl.m4	25 Jan 2006 21:52:11 -0000	1.3
+++ tclconfig/tcl.m4	30 May 2009 11:51:23 -0000
@@ -181,10 +181,12 @@
 #
 #	Adds the following arguments to configure:
 #		--with-tk=...
+#		--with-tk=no disable Tk usage
 #
 #	Defines the following vars:
 #		TK_BIN_DIR	Full path to the directory containing
 #				the tkConfig.sh file
+#				Empty if Tk is disabled
 #------------------------------------------------------------------------
 
 AC_DEFUN(TEA_PATH_TKCONFIG, [
@@ -201,6 +203,12 @@
 	    AC_HELP_STRING([--with-tk],
 		[directory containing tk configuration (tkConfig.sh)]),
 	    with_tkconfig=${withval})
+
+	if test x"${with_tkconfig}" = x"no" ; then
+	    AC_MSG_RESULT([Tk is disabled by --with-tk=no])
+	    unset TK_BIN_DIR
+	else
+
 	AC_MSG_CHECKING([for Tk configuration])
 	AC_CACHE_VAL(ac_cv_c_tkconfig,[
 
@@ -309,6 +317,7 @@
 	    TK_BIN_DIR=${ac_cv_c_tkconfig}
 	    AC_MSG_RESULT([found ${TK_BIN_DIR}/tkConfig.sh])
 	fi
+	fi
     fi
 ])
 
@@ -420,6 +429,7 @@
 #------------------------------------------------------------------------
 
 AC_DEFUN(TEA_LOAD_TKCONFIG, [
+    if test x"${with_tkconfig}" != x"no" ; then
     AC_MSG_CHECKING([for existence of ${TK_BIN_DIR}/tkConfig.sh])
 
     if test -f "${TK_BIN_DIR}/tkConfig.sh" ; then
@@ -501,6 +511,7 @@
 
     AC_SUBST(TK_LIBS)
     AC_SUBST(TK_XINCLUDES)
+    fi
 ])
 
 #------------------------------------------------------------------------
@@ -3528,6 +3539,11 @@
 #------------------------------------------------------------------------
 
 AC_DEFUN(TEA_PUBLIC_TK_HEADERS, [
+    if test x"${with_tkconfig}" = x"no" ; then
+	TK_INCLUDES=""
+	AC_SUBST(TK_INCLUDES)
+    else
+
     AC_MSG_CHECKING([for Tk public headers])
 
     AC_ARG_WITH(tkinclude, [  --with-tkinclude      directory containing the public Tk header files.], with_tkinclude=${withval})
@@ -3608,6 +3624,7 @@
 	fi
 	AC_MSG_RESULT([${INCLUDE_DIR_NATIVE}])
     fi
+    fi
 ])
 
 #------------------------------------------------------------------------