Merge branch 'inet-siphash'

Eric Dumazet says:

====================
inet: use siphash in exception handling

A group of security researchers brought to our attention
the weakness of hash functions used in rt6_exception_hash()
and fnhe_hashfun()

I made two distinct patches to help backports, since IPv6
part was added in 4.15
====================

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