Add ip rule flush capabilty and fix all the prototype changes
because of that code rewrites the nlmsghdr.

(Logical change 1.106)
diff --git a/include/libnetlink.h b/include/libnetlink.h
index 3390d8b..08be752 100644
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -20,7 +20,8 @@
 extern int rtnl_wilddump_request(struct rtnl_handle *rth, int fam, int type);
 extern int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len);
 
-typedef int (*rtnl_filter_t)(const struct sockaddr_nl *, const struct nlmsghdr *n, void *);
+typedef int (*rtnl_filter_t)(const struct sockaddr_nl *, 
+			     struct nlmsghdr *n, void *);
 extern int rtnl_dump_filter(struct rtnl_handle *rth, rtnl_filter_t filter,
 			    void *arg1,
 			    rtnl_filter_t junk,