pc: disable acpi info for isapc and old pc machine

Disable acpi build for isapc and no_kvmclock machine
types (used by xen), since acpi build currently expects pci.

Reported-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

hw/i386/pc_piix.c

@@ -309,6 +309,7 @@ static void pc_init_pci_1_2(QEMUMachineInitArgs *args)
 static void pc_init_pci_no_kvmclock(QEMUMachineInitArgs *args)
 {
     has_pci_info = false;
+    has_acpi_build = false;
     disable_kvm_pv_eoi();
     enable_compat_apic_id_mode();
     pc_init1(args, 1, 0);
@@ -317,6 +318,7 @@ static void pc_init_pci_no_kvmclock(QEMUMachineInitArgs *args)
 static void pc_init_isa(QEMUMachineInitArgs *args)
 {
     has_pci_info = false;
+    has_acpi_build = false;
     if (!args->cpu_model) {
         args->cpu_model = "486";
     }