rough-draft VKERNEL host-initiated shutdown patch

[Chris Turner]

Matthew Dillon wrote:
> :Disclaimer: MESSY!
> :
> :Took a quick attempt at getting the VKERNEL to shutdown cleanly against
> :1.8,
> :and it seems to work just fine as suggested with mailbox signals, etc.
> :

realise I hadn't responsed .. thanks for feeback. will try to cleanup
soonish & resubmit.

how's HEAD stabilizing, or is Preview a better bet for patch testing?

Thanks,

- Chris