[PATCH v2] vhost: fix external message handlers

[Poczatek, Jakub]

Hi everyone, 

> Following a rework, external message handlers were receiving a pointer 
> to a vhost_user message (as stated in the API), but lost the ability 
> to interact with fds attached to the message.
> Restore the original layout and put a build check and reminders.
> 
> Bugzilla ID: 953
> Fixes: 5e0099dc709e ("vhost: remove payload size limitation")
> 
> Reported-by: Fan Zhang <roy.fan.zhang at intel.com>
> Signed-off-by: David Marchand <david.marchand at redhat.com>
> ---
> Changes since v1:
> - fixed build with clang,
> 
> ---

Tested-by: Jakub Poczatek <Jakub.poczatek at intel.com>
Acked-by: Jakub Poczatek <Jakub.poczatek at intel.com>