Fixed IPv4-in-IPv6 and IPv6-in-IPv4 IPsec tunnels.
For IPv6-in-IPv4, you may need to do the following command
on the tunnel interface if it is configured as IPv4 only:
ifconfig <interface> inet6 -ifdisabled

Code logic inspired from NetBSD.

PR: kern/169438
Submitted by: emeric.poupon@netasq.com
Reviewed by: fabient, ae
Obtained from: NETASQ
Remove nop.

MFC after:	1 week
Use M_WAITOK for the NGM_PIPE_SET_CFG control message. We expect it to
arrive from userland only.

Submitted by:	Dmitry Luhtionov <dmitryluhtionov gmail.com>