qemu-spoof: clear the SMBIOS type0 "VM" characteristic bit

type0 bios-characteristics-extension byte sets bit 0x10 ("VM") for QEMU; suppress
it when spoof_smbios_hide_vm(). (type1/2/3 manufacturer/product/serial are the
config layer; type4 socket / type11 OEM-strings / type17 memory wiring is a
follow-up.) Inert unless a spoof-seed is set.
diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
index 7d71418..4c39b5a 100644
--- a/hw/smbios/smbios.c
+++ b/hw/smbios/smbios.c
@@ -16,6 +16,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "hw/misc/spoof.h"
 #include "qemu/units.h"
 #include "qemu/bswap.h"
 #include "qapi/error.h"
@@ -583,7 +584,7 @@ static void smbios_build_type_0_table(void)
     if (smbios_type0.uefi) {
         t->bios_characteristics_extension_bytes[1] |= 0x08; /* |= UEFI */
     }
-    if (smbios_type0.vm) {
+    if (smbios_type0.vm && !spoof_smbios_hide_vm()) {
         t->bios_characteristics_extension_bytes[1] |= 0x10; /* |= VM */
     }