Adding also our copy of struct rtvia.

configure.in

@@ -219,6 +219,7 @@ esac
 AC_CHECK_HEADER(syslog.h, [AC_DEFINE(HAVE_SYSLOG)])
 AC_CHECK_HEADER(alloca.h, [AC_DEFINE(HAVE_ALLOCA_H)])
 AC_CHECK_HEADER([linux/lwtunnel.h], [AC_DEFINE(HAVE_LWTUNNEL)])
+AC_CHECK_MEMBERS([struct rtvia.rtvia_family], [AC_DEFINE(HAVE_STRUCT_RTVIA)],,[#include <linux/rtnetlink.h>])
 AC_MSG_CHECKING(whether 'struct sockaddr' has sa_len)
 AC_TRY_COMPILE([#include <sys/types.h>
   #include <sys/socket.h>

sysdep/autoconf.h.in

@@ -77,4 +77,7 @@
 /* We have linux lwtunnel */
 #undef HAVE_LWTUNNEL
 
+/* We have struct rtvia */
+#undef HAVE_STRUCT_RTVIA
+
 #define CONFIG_PATH ?

sysdep/linux/netlink.c

@@ -60,6 +60,13 @@
 #define RTA_VIA	 18
 #endif
 
+#ifndef HAVE_STRUCT_RTVIA
+struct rtvia {
+	__kernel_sa_family_t	rtvia_family;
+	__u8			rtvia_addr[0];
+};
+#endif
+
 #ifndef RTA_NEWDST
 #define RTA_NEWDST  19
 #endif