[IPV4]: reset IPCB flags when neccessary

Reset IPSKB_XFRM_TUNNEL_SIZE flags in ipip and ip_gre hard_start_xmit
function before the packet reenters IP. This is neccessary so the
encapsulated packets are checked not to be oversized in xfrm4_output.c
again. Reset all flags in sit when a packet changes its address family.

Also remove some obsolete IPSKB flags.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 577d497..02872ae 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -381,6 +381,7 @@
 		skb->mac.raw = skb->nh.raw;
 		skb->nh.raw = skb->data;
 		memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
+		IPCB(skb)->flags = 0;
 		skb->protocol = htons(ETH_P_IPV6);
 		skb->pkt_type = PACKET_HOST;
 		tunnel->stat.rx_packets++;
@@ -552,6 +553,7 @@
 	skb->h.raw = skb->nh.raw;
 	skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
+	IPCB(skb)->flags = 0;
 	dst_release(skb->dst);
 	skb->dst = &rt->u.dst;