extensions: add connlabel match

allows to "tag" connections with up to 128 label names.

Labels are defined in /etc/xtables/connlabel.conf, example:
0 from eth0
1 via eth0

Labels can then be attached to flows, e.g.

-A PREROUTING  -i eth0 -m connlabel --label "from eth0" --set

Signed-off-by: Florian Westphal <fw@strlen.de>
diff --git a/Makefile.am b/Makefile.am
index c38d360..cd008a1 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -24,5 +24,9 @@
 	tar -C /tmp -cjf ${PACKAGE_TARNAME}-${PACKAGE_VERSION}.tar.bz2 --owner=root --group=root ${PACKAGE_TARNAME}-${PACKAGE_VERSION}/;
 	rm -Rf /tmp/${PACKAGE_TARNAME}-${PACKAGE_VERSION};
 
+install-data-hook:
+	@mkdir -p -m 755 $(DESTDIR)/etc/xtables/ || :
+	@test -f /etc/xtables/connlabel.conf || $(INSTALL) -m 644 etc/xtables/connlabel.conf $(DESTDIR)/etc/xtables/connlabel.conf || :
+
 config.status: extensions/GNUmakefile.in \
 	include/xtables-version.h.in include/iptables/internal.h.in