libxc/x86: Report consistent initial APIC value for PV guests

libxc/x86: Report consistent initial APIC value for PV guests

Currently hypervisor provides PV guest's CPUID(1).EBX[31:24] (initial
APIC ID) with contents of that field on the processor that launched
the guest. This results in the guest reporting different initial
APIC IDs across runs.

We should be consistent in how this value is reported, let's set
it to 0 (which is also what Linux guests expect).

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
[ wei: remove trailing whitespace in comment ]
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>