qemu: Clear autofil fill flag when pinning iothread

https://bugzilla.redhat.com/show_bug.cgi?id=1218577

Treat pinning an IOThread via API as if someone added an IOThread to
ensure the iothreadid doesn't cause the guest to disappear

src/qemu/qemu_driver.c

@@ -6016,6 +6016,7 @@ qemuDomainPinIOThread(virDomainPtr dom,
 
         virBitmapFree(iothrid->cpumask);
         iothrid->cpumask = cpumask;
+        iothrid->autofill = false;
 
         /* Configure the corresponding cpuset cgroup before set affinity. */
         if (virCgroupHasController(priv->cgroup,
@@ -6072,6 +6073,7 @@ qemuDomainPinIOThread(virDomainPtr dom,
 
         virBitmapFree(iothrid->cpumask);
         iothrid->cpumask = cpumask;
+        iothrid->autofill = false;
 
         ret = virDomainSaveConfig(cfg->configDir, persistentDef);
         goto endjob;