tcp: remove stale sysctl_tcp_reordering

This extern is no longer used.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -244,7 +244,6 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
 
 /* sysctl variables for tcp */
 extern int sysctl_tcp_max_orphans;
-extern int sysctl_tcp_reordering;
 extern int sysctl_tcp_max_reordering;
 extern int sysctl_tcp_dsack;
 extern long sysctl_tcp_mem[3];