net: Use bool in skbuff.h helper functions.

In particular do this for skb_is_nonlinear(), skb_is_gso(), and
skb_is_gso_v6().

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 79ef820..8dc8257 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1173,7 +1173,7 @@
 }
 
 
-static inline int skb_is_nonlinear(const struct sk_buff *skb)
+static inline bool skb_is_nonlinear(const struct sk_buff *skb)
 {
 	return skb->data_len;
 }
@@ -2469,12 +2469,12 @@
 }
 #endif
 
-static inline int skb_is_gso(const struct sk_buff *skb)
+static inline bool skb_is_gso(const struct sk_buff *skb)
 {
 	return skb_shinfo(skb)->gso_size;
 }
 
-static inline int skb_is_gso_v6(const struct sk_buff *skb)
+static inline bool skb_is_gso_v6(const struct sk_buff *skb)
 {
 	return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
 }