qemu-spoof: route ACPI table header identity through the spoof module

acpi_table_begin(): OEM id / OEM table id / creator id now come from
spoof_acpi_*(); build_fadt(): blank the "QEMU" hypervisor-vendor when spoofing.
All inert (return the stock default) unless a spoof-seed is set.
diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
index 4b37405..8bc3f4d 100644
--- a/hw/acpi/aml-build.c
+++ b/hw/acpi/aml-build.c
@@ -20,6 +20,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "hw/misc/spoof.h"
 #include <glib/gprintf.h>
 #include "hw/acpi/aml-build.h"
 #include "hw/acpi/acpi.h"
@@ -1725,11 +1726,11 @@ void acpi_table_begin(AcpiTable *desc, GArray *array)
     build_append_int_noprefix(array, 0, 4); /* Length */
     build_append_int_noprefix(array, desc->rev, 1); /* Revision */
     build_append_int_noprefix(array, 0, 1); /* Checksum */
-    build_append_padded_str(array, desc->oem_id, 6, '\0'); /* OEMID */
+    build_append_padded_str(array, spoof_acpi_oem_id(desc->oem_id), 6, '\0'); /* OEMID */
     /* OEM Table ID */
-    build_append_padded_str(array, desc->oem_table_id, 8, '\0');
+    build_append_padded_str(array, spoof_acpi_oem_table_id(desc->oem_table_id), 8, '\0');
     build_append_int_noprefix(array, 1, 4); /* OEM Revision */
-    g_array_append_vals(array, ACPI_BUILD_APPNAME8, 4); /* Creator ID */
+    g_array_append_vals(array, spoof_acpi_creator_id(ACPI_BUILD_APPNAME8), 4); /* Creator ID */
     build_append_int_noprefix(array, 1, 4); /* Creator Revision */
 }
 
@@ -2370,7 +2371,7 @@ void build_fadt(GArray *tbl, BIOSLinker *linker, const AcpiFadtData *f,
     }
 
     /* Hypervisor Vendor Identity */
-    build_append_padded_str(tbl, "QEMU", 8, '\0');
+    build_append_padded_str(tbl, spoof_enabled() ? "" : "QEMU", 8, '\0');
 
     /* TODO: extra fields need to be added to support revisions above rev6 */
     assert(f->rev == 6);