vmapple: give apple-vm the vmapple compat properties

machine_class_base_init() gives every concrete machine class a fresh
compat_props array, so apple-vm did not inherit vmapple's defaults:
virtio-pci devices came up transitional (virtio-net as 1af4:1000
instead of 1af4:1041), and the XHCI lost conditional-intr-mapping,
which mach_vmapple_init() now also sets directly.

Mark disable-legacy optional, as other machines do. The transitional
and non-transitional virtio-pci types have no such property, and a
non-optional global aborts QEMU when one of them is created, on -M
vmapple too.

Signed-off-by: awaiiro <332003006+awaiiro@users.noreply.github.com>

qemu/hw/vmapple/vmapple.c

@@ -712,7 +712,8 @@ static const CPUArchIdList *vmapple_possible_cpu_arch_ids(MachineState *ms)
 }
 
 static GlobalProperty vmapple_compat_defaults[] = {
-    { TYPE_VIRTIO_PCI, "disable-legacy", "on" },
+    /* Optional: transitional and non-transitional types have no such property */
+    { TYPE_VIRTIO_PCI, "disable-legacy", "on", .optional = true },
     /*
      * macOS XHCI driver attempts to schedule events onto even rings 1 & 2
      * even when (as here) there is no MSI(-X) support. Disabling interrupter
@@ -803,6 +804,13 @@ static void apple_vm_machine_class_init(ObjectClass *oc, const void *data)
     /* Parent (vmapple) class_init has already run; override only the CPU. */
     mc->default_cpu_type = TYPE_APPLE_VM_CPU;
     mc->desc = "Apple aarch64 Virtual Machine (Orchard, custom CPU)";
+
+    /*
+     * Except compat_props: machine_class_base_init() gives every concrete
+     * machine class a fresh array, so the parent's defaults are not inherited.
+     */
+    compat_props_add(mc->compat_props, vmapple_compat_defaults,
+                     G_N_ELEMENTS(vmapple_compat_defaults));
 }
 
 static const TypeInfo apple_vm_machine_info = {