libxc/xen: introduce a start info structure for HVMlite guests

libxc/xen: introduce a start info structure for HVMlite guests

This structure contains the physical address of the command line, as well as
the physical address of the list of loaded modules. The physical address of
this structure is passed to the guest at boot time in the %ebx register.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>