tests/acpi: don't pack a structure

There's no reason to pack structures where we don't care about size or
padding, this applies to AcpiStdTable in tests/acpi-utils.h.

OTOH bios-tables-test happens to be passing the address of a field in
this  struct to a function that expects a pointer to normally aligned
data which results in a SIGBUS on architectures like SPARC that have
strict alignment requirements.

Fixes: 9e8458c0 ("acpi unit-test: compare DSDT and SSDT tables against expected values")
Reported-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Tested-by: NPeter Maydell <peter.maydell@linaro.org>

tests/acpi-utils.h

@@ -26,7 +26,7 @@ typedef struct {
     gsize asl_len;
     gchar *asl_file;
     bool tmp_files_retain;   /* do not delete the temp asl/aml */
-} QEMU_PACKED AcpiSdtTable;
+} AcpiSdtTable;
 
 #define ACPI_READ_FIELD(field, addr)           \
     do {                                       \