iproute2: detect iptables modules dir in configure.

Try to automatically detect iptables modules directory.

Make the configure script look for iptables modules.
This also makes it possible to specify it on the
command line while building via "make IPT_LIB_DIR=/foo/bar".

Signed-off-by: Andreas Henriksson <andreas@fatal.se>
diff --git a/configure b/configure
index 92a0b48..600fa96 100755
--- a/configure
+++ b/configure
@@ -3,6 +3,8 @@
 #
 INCLUDE=${1:-"$PWD/include"}
 
+TABLES=
+
 check_atm()
 {
 cat >/tmp/atmtest.c <<EOF
@@ -139,9 +141,28 @@
 	if ! grep TC_CONFIG_XT Config > /dev/null
 	then
 		echo "using iptables"
+		TABLES="iptables"
+	else
+		TABLES="xtables"
 	fi
 }
 
+check_ipt_lib_dir()
+{
+	IPT_LIB_DIR=""
+	for dir in /lib /usr/lib /usr/local/lib
+	do
+		for file in $dir/$TABLES/lib*t_*so ; do
+			if [ -f $file ]; then
+				echo $dir/$TABLES
+				echo "IPT_LIB_DIR:=$dir/$TABLES" >> Config
+				return
+			fi
+		done
+	done
+	echo "not found!"
+}
+
 echo "# Generated config based on" $INCLUDE >Config
 
 echo "TC schedulers"
@@ -155,3 +176,5 @@
 check_xt_old_internal_h
 check_ipt
 
+echo -n "iptables modules directory: "
+check_ipt_lib_dir