[NET]: Treat the sign of the result of skb_headroom() consistently

In some places, the result of skb_headroom() is compared to an unsigned
integer, and in others, the result is compared to a signed integer.  Make
the comparisons consistent and correct.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ipvs/ip_vs_xmit.c b/net/ipv4/ipvs/ip_vs_xmit.c
index d0a92de..7c074e3 100644
--- a/net/ipv4/ipvs/ip_vs_xmit.c
+++ b/net/ipv4/ipvs/ip_vs_xmit.c
@@ -325,7 +325,7 @@
 	__be16 df = old_iph->frag_off;
 	sk_buff_data_t old_transport_header = skb->transport_header;
 	struct iphdr  *iph;			/* Our new IP header */
-	int    max_headroom;			/* The extra header space needed */
+	unsigned int max_headroom;		/* The extra header space needed */
 	int    mtu;
 
 	EnterFunction(10);