net: ipv4: export fib_lookup and fib_table_lookup

The reverse path filter module will use fib_lookup.

If CONFIG_IP_MULTIPLE_TABLES is not set, fib_lookup is
only a static inline helper that calls fib_table_lookup,
so export that too.
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/ipv4/fib_rules.c

@@ -67,6 +67,7 @@ int fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
 
 	return err;
 }
+EXPORT_SYMBOL_GPL(fib_lookup);
 
 static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
 			    int flags, struct fib_lookup_arg *arg)

net/ipv4/fib_trie.c

@@ -1607,6 +1607,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
 	rcu_read_unlock();
 	return ret;
 }
+EXPORT_SYMBOL_GPL(fib_table_lookup);
 
 /*
  * Remove the leaf and return parent.