pc: Generate APIC IDs according to CPU topology

pc: Generate APIC IDs according to CPU topology

This keeps compatibility on machine-types pc-1.2 and older, and prints a
warning in case the requested configuration won't get the correct
topology.

I couldn't think of a better way to warn about broken topology when in
compat mode other than using error_report(). The warning message will
probably be buried in a log file somewhere, but it's better than
nothing.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>