[PKT_SCHED]: ipt action: add back pskb_expand_head() call

Jamal asked me to add back the call to pskb_expand_head before 2.6.11.
This fixes a regression caused by my tc action cleanup patches, the
tc actions most not replace packets, so it must prevent netfilter from
doing so.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/ipt.c

@@ -207,6 +207,11 @@ tcf_ipt(struct sk_buff **pskb, struct tc_action *a)
 	struct tcf_ipt *p = PRIV(a, ipt);
 	struct sk_buff *skb = *pskb;
 
+	if (skb_cloned(skb)) {
+		if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+			return TC_ACT_UNSPEC;
+	}
+
 	spin_lock(&p->lock);
 
 	p->tm.lastuse = jiffies;