[TCP]: Kill unused extern decl for tcp_v4_hash_connecting()

Noticed by Alan Menegotto.
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -405,9 +405,6 @@ extern int			tcp_disconnect(struct sock *sk, int flags);
 
 extern void			tcp_unhash(struct sock *sk);
 
-extern int			tcp_v4_hash_connecting(struct sock *sk);
-
-
 /* From syncookies.c */
 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 
 				    struct ip_options *opt);