Fix for missing definitions on some Hardened configurations
Gentoo bug: https://bugs.gentoo.org/show_bug.cgi?id=437292

diff -Naur quagga-0.99.16.orig/zebra/ipforward_sysctl.c quagga-0.99.16/zebra/ipforward_sysctl.c
--- quagga-0.99.16.orig/zebra/ipforward_sysctl.c	2010-03-11 12:11:32.000000000 -0500
+++ quagga-0.99.16/zebra/ipforward_sysctl.c	2010-03-11 12:11:39.000000000 -0500
@@ -31,6 +31,15 @@
 
 #define MIB_SIZ 4
 
+/* Fix for recent (2.6.14) kernel headers */
+#ifndef IPCTL_FORWARDING
+    #define IPCTL_FORWARDING       NET_IPV4_FORWARD
+#endif
+
+#ifndef IP6CTL_FORWARDING
+    #define IP6CTL_FORWARDING      NET_IPV6_FORWARDING
+#endif
+
 extern struct zebra_privs_t zserv_privs;
 
 /* IPv4 forwarding control MIB. */