iptables: Fix connlabel.conf install location

As reported by Danny Rawlins in bug #828, connlabel.conf is
unconditionally installed in /etc/xtables instead of using
prefix set at configure time. Fix to use sysconfdir variable.

This closes bugzilla #828.

Signed-off-by: Phil Oester <kernel@linuxace.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/Makefile.am b/Makefile.am
index cd008a1..73f1352 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -25,8 +25,8 @@
 	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 || :
+	@mkdir -p -m 755 @sysconfdir@/xtables/ || :
+	@test -f @sysconfdir@/xtables/connlabel.conf || $(INSTALL) -m 644 etc/xtables/connlabel.conf @sysconfdir@/xtables/connlabel.conf || :
 
 config.status: extensions/GNUmakefile.in \
 	include/xtables-version.h.in include/iptables/internal.h.in