[ICMP]: Dst entry leak in icmp_send host re-lookup code (v2).

Commit 8b7817f3 ([IPSEC]: Add ICMP host
relookup support) introduced some dst leaks on error paths: the rt
pointer can be forgotten to be put. Fix it bu going to a proper label.

Found after net namespace's lo refused to unregister :) Many thanks to 
Den for valuable help during debugging.

Herbert pointed out, that xfrm_lookup() will put the rtable in case
of error itself, so the first goto fix is redundant.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/icmp.c

@@ -591,7 +591,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 		}
 
 		if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET))
-			goto out_unlock;
+			goto ende;
 
 		if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL)
 			err = __ip_route_output_key(net, &rt2, &fl);
@@ -601,7 +601,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 
 			fl2.fl4_dst = fl.fl4_src;
 			if (ip_route_output_key(net, &rt2, &fl2))
-				goto out_unlock;
+				goto ende;
 
 			/* Ugh! */
 			odst = skb_in->dst;
@@ -614,7 +614,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 		}
 
 		if (err)
-			goto out_unlock;
+			goto ende;
 
 		err = xfrm_lookup((struct dst_entry **)&rt2, &fl, NULL,
 				  XFRM_LOOKUP_ICMP);