Reset system before loadvm

In case we load the vmstate during incoming migration, we start from a
clean, default machine state as we went through system reset before. But
if we load from a snapshot, the machine can be in any state. That can
cause troubles if loading an older image which does not carry all state
information the executing QEMU requires. Hardly any device takes care of
this scenario.

However, fixing this is trivial. We just need to issue a system reset
during loadvm as well.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

savevm.c

@@ -2073,6 +2073,7 @@ int load_vmstate(const char *name)
         return -EINVAL;
     }
 
+    qemu_system_reset(VMRESET_SILENT);
     ret = qemu_loadvm_state(f);
 
     qemu_fclose(f);