Merge branch 'ipv6-better-traceroute-sit-gre'

Eric Dumazet says:

====================
ipv6: better traceroute support in sit and gre

In commit ca15a078 ("sit: generate icmpv6 error when receiving icmpv4
error"), Oussama Ghorbel added minimal support for SIT tunnels to
generate ICMPv6 messages when receiving ICMPv4 messages.

This patch series extends this to GRE tunnels.

It also adds support for ICMPV6_TIME_EXCEED.

Partial support for RFC 4884 is added, to forward ICMP Multi-part
extensions eventually found in the ICMPv4 message.

v2: replaced an overlapping memcpy() by memmove()
====================

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