Fix compile errors after r297225:

- properly V_irtualise variable access unbreaking VIMAGE kernels.
- remove the volatile from the function return type to make architecture
  using gcc happy [-Wreturn-type]
  "type qualifiers ignored on function return type"
  I am not entirely happy with this solution putting the u_int there
  but it will do for now.

sys/net/route.c

@@ -201,7 +201,7 @@ rt_tables_get_rnh(int table, int fam)
 	return (*rt_tables_get_rnh_ptr(table, fam));
 }
 
-rt_gen_t
+u_int
 rt_tables_get_gen(int table, int fam)
 {
 	struct rib_head *rnh;

sys/net/route.h

@@ -437,7 +437,7 @@ int	 rt_setgate(struct rtentry *, struct sockaddr *, struct sockaddr *);
 void 	 rt_maskedcopy(struct sockaddr *, struct sockaddr *, struct sockaddr *);
 struct rib_head *rt_table_init(int);
 void	rt_table_destroy(struct rib_head *);
-rt_gen_t rt_tables_get_gen(int table, int fam);
+u_int	rt_tables_get_gen(int table, int fam);
 
 int	rtsock_addrmsg(int, struct ifaddr *, int);
 int	rtsock_routemsg(int, struct ifnet *ifp, int, struct rtentry *, int);

sys/netinet/tcp_subr.c

@@ -1932,7 +1932,7 @@ tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
 		notify = tcp_drop_syn_sent;
 	else if (PRC_IS_REDIRECT(cmd)) {
 		/* signal EHOSTDOWN, as it flushes the cached route */
-		in_pcbnotifyall(&tcbinfo, faddr, EHOSTDOWN, notify);
+		in_pcbnotifyall(&V_tcbinfo, faddr, EHOSTDOWN, notify);
 		return;
 	}
 	/*

sys/netinet/udp_usrreq.c

@@ -768,7 +768,7 @@ udp_common_ctlinput(int cmd, struct sockaddr *sa, void *vip,
 
 	if (PRC_IS_REDIRECT(cmd)) {
 		/* signal EHOSTDOWN, as it flushes the cached route */
-		in_pcbnotifyall(&udbinfo, faddr, EHOSTDOWN, udp_notify);
+		in_pcbnotifyall(&V_udbinfo, faddr, EHOSTDOWN, udp_notify);
 		return;
 	}