Last fixes from 6Wind patch.
diff --git a/zebra/interface.h b/zebra/interface.h
index dbfa822..3ab624f 100644
--- a/zebra/interface.h
+++ b/zebra/interface.h
@@ -31,7 +31,9 @@
 
 /* Router advertisement feature. */
 #if (defined(LINUX_IPV6) && (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1)) || defined(KAME)
-#define RTADV
+  #ifdef HAVE_RTADV
+    #define RTADV
+  #endif
 #endif
 
 #ifdef RTADV