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>
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 0c06847..b7eb51e 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1093,7 +1093,7 @@
 	memset(&fl6, 0, sizeof(fl6));
 	fl6.flowi6_oif = oif;
 	fl6.flowi6_mark = mark;
-	fl6.flowi6_flags = FLOWI_FLAG_PRECOW_METRICS;
+	fl6.flowi6_flags = 0;
 	fl6.daddr = iph->daddr;
 	fl6.saddr = iph->saddr;
 	fl6.flowlabel = (*(__be32 *) iph) & IPV6_FLOWINFO_MASK;