powerpc pci: fixed packing of ranges[]

By default mingw-gcc is trying to pack structures the way to
preserve binary compatibility with MS Visual C what leads to
incorrect and unexpected padding in the PCI bus ranges property of
the sPAPR PHB.

The patch replaces __attribute__((packed)) with more strict QEMU_PACKED
which actually is __attribute__((gcc_struct, packed)) on Windows.
Signed-off-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
Tested-by: NStefan Weil <sw@weilnetz.de>
Reviewed-by: NStefan Weil <sw@weilnetz.de>
Acked-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

hw/spapr_pci.c

@@ -418,7 +418,7 @@ int spapr_populate_pci_devices(sPAPRPHBState *phb,
         uint64_t child;
         uint64_t parent;
         uint64_t size;
-    } __attribute__((packed)) ranges[] = {
+    } QEMU_PACKED ranges[] = {
         {
             cpu_to_be32(b_ss(1)), cpu_to_be64(0),
             cpu_to_be64(phb->io_win_addr),