inet: Kill FLOWI_FLAG_PRECOW_METRICS.

No longer needed.  TCP writes metrics, but now in it's own special
cache that does not dirty the route metrics.  Therefore there is no
longer any reason to pre-cow metrics in this way.

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

include/net/inet_sock.h

@@ -245,8 +245,6 @@ static inline __u8 inet_sk_flowi_flags(const struct sock *sk)
 
 	if (inet_sk(sk)->transparent || inet_sk(sk)->hdrincl)
 		flags |= FLOWI_FLAG_ANYSRC;
-	if (sk->sk_protocol == IPPROTO_TCP)
-		flags |= FLOWI_FLAG_PRECOW_METRICS;
 	return flags;
 }