ipv4: Remove rt_key_{src,dst,tos} from struct rtable.

They are always used in contexts where they can be reconstituted,
or where the finally resolved rt->rt_{src,dst} is semantically
equivalent.

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

diff --cc include/net/route.h
Simple merge

diff --cc net/ipv4/route.c
Simple merge

diff --cc net/ipv4/xfrm4_policy.c
Simple merge