hw/i386: changes towards enabling -Wshadow=local for x86 machines

Code changes that addresses all compiler complaints coming from enabling
-Wshadow flags. Enabling -Wshadow catches cases of local variables shadowing
other local variables or parameters. These makes the code confusing and/or adds
bugs that are difficult to catch.

See also

   Subject: Help wanted for enabling -Wshadow=local
   Message-Id: <87r0mqlf9x.fsf@pond.sub.org>
   https://lore.kernel.org/qemu-devel/87r0mqlf9x.fsf@pond.sub.org

CC: Markus Armbruster <armbru@redhat.com>
CC: Philippe Mathieu-Daude <philmd@linaro.org>
CC: mst@redhat.com

Signed-off-by: Ani Sinha <anisinha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-ID: <20231003102803.6163-1-anisinha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

hw/i386/acpi-microvm.c

@@ -55,8 +55,8 @@ static void acpi_dsdt_add_virtio(Aml *scope,
 
     bus = sysbus_get_default();
     QTAILQ_FOREACH(kid, &bus->children, sibling) {
-        DeviceState *dev = kid->child;
-        Object *obj = object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MMIO);
+        Object *obj = object_dynamic_cast(OBJECT(kid->child),
+                                          TYPE_VIRTIO_MMIO);
 
         if (obj) {
             VirtIOMMIOProxy *mmio = VIRTIO_MMIO(obj);

hw/i386/pc.c

@@ -1049,7 +1049,6 @@ void pc_memory_init(PCMachineState *pcms,
 
     if (machine->device_memory) {
         uint64_t *val = g_malloc(sizeof(*val));
-        PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
         uint64_t res_mem_end = machine->device_memory->base;
 
         if (!pcmc->broken_reserved_end) {

hw/i386/x86.c

@@ -365,8 +365,6 @@ void x86_cpu_pre_plug(HotplugHandler *hotplug_dev,
 
     cpu_slot = x86_find_cpu_slot(MACHINE(x86ms), cpu->apic_id, &idx);
     if (!cpu_slot) {
-        MachineState *ms = MACHINE(x86ms);
-
         x86_topo_ids_from_apicid(cpu->apic_id, &topo_info, &topo_ids);
         error_setg(errp,
             "Invalid CPU [socket: %u, die: %u, core: %u, thread: %u] with"