Fixes for domains with no iothreads

Plug a memory leak and silence a warning.

src/qemu/qemu_cgroup.c

@@ -1131,7 +1131,7 @@ qemuSetupCgroupForIOThreads(virDomainObjPtr vm)
     if (priv->cgroup == NULL)
         return 0;
 
-    if (priv->niothreadpids == 0) {
+    if (def->iothreads && priv->niothreadpids == 0) {
         VIR_WARN("Unable to get iothreads' pids.");
         return 0;
     }

src/qemu/qemu_process.c

@@ -2117,8 +2117,10 @@ qemuProcessDetectIOThreadPIDs(virQEMUDriverPtr driver,
         goto cleanup;
 
     /* Nothing to do */
-    if (niothreads == 0)
-        return 0;
+    if (niothreads == 0) {
+        ret = 0;
+        goto cleanup;
+    }
 
     if (niothreads != vm->def->iothreads) {
         virReportError(VIR_ERR_INTERNAL_ERROR,