This patch moves xfrm[46]_tunnel_check_size() into xfrm[46]_output.c
where it can be made static since it's only used there.

While moving the icmp.h inclusions over I also discovered that the
tunnel files are missing an inclusion of net/protocol.h.  So I've
added them as well.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@redhat.com>