Use some preprocessor tricks to route around incompatibilies seen
between newer Linux kernels and glibc when both net/if.h and linux/if.h
are included in the same source.

Patch from gentoo, see https://bugs.gentoo.org/show_bug.cgi?id=577584

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>

--- connman-1.31/src/iptables.c.old	2016-03-22 20:12:47.829460752 -0700
+++ connman-1.31/src/iptables.c	2016-03-22 21:33:36.835384724 -0700
@@ -28,11 +28,11 @@
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 #include <sys/errno.h>
 #include <sys/socket.h>
-#include <xtables.h>
+#include "connman_xtables.h"
 #include <inttypes.h>
 
 #include <linux/netfilter_ipv4/ip_tables.h>
 
 #include "connman.h"
--- connman-1.31/src/firewall.c.old	2016-03-22 21:29:01.959472262 -0700
+++ connman-1.31/src/firewall.c	2016-03-22 21:33:53.048144181 -0700
@@ -23,11 +23,11 @@
 #include <config.h>
 #endif
 
 #include <errno.h>
 
-#include <xtables.h>
+#include "connman_xtables.h"
 #include <linux/netfilter_ipv4/ip_tables.h>
 
 #include "connman.h"
 
 #define CHAIN_PREFIX "connman-"
--- /dev/null	2016-03-18 06:21:16.372989086 -0700
+++ connman-1.31/include/connman_xtables.h	2016-03-22 21:32:21.349504786 -0700
@@ -0,0 +1,20 @@
+#ifndef CONNMAN_XTABLES_H
+#define CONNMAN_XTABLES_H
+
+#include <linux/version.h>
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 5, 0)
+#include <xtables.h>
+#else
+#ifdef __USE_MISC
+#define GENTOO_USE_MISC __USE_MISC
+#undef __USE_MISC
+#endif
+
+#include <xtables.h>
+
+#ifdef GENTOO_USE_MISC
+#define __USE_MISC GENTOO_USE_MISC
+#undef GENTOO_USE_MISC
+#endif
+#endif
+#endif