qemu: Restart CPUs with valid async job type when doing external snapshots

When restarting CPUs after an external snapshot, the restarting function
was called without the appropriate async job type. This caused that a
new sync job wasn't created and allowed races in the monitor.

src/qemu/qemu_driver.c

@@ -11482,7 +11482,7 @@ endjob:
     if (resume && vm && virDomainObjIsActive(vm) &&
         qemuProcessStartCPUs(driver, vm, conn,
                              VIR_DOMAIN_RUNNING_UNPAUSED,
-                             QEMU_ASYNC_JOB_NONE) < 0) {
+                             QEMU_ASYNC_JOB_SNAPSHOT) < 0) {
         virDomainEventPtr event = NULL;
         event = virDomainEventNewFromObj(vm,
                                          VIR_DOMAIN_EVENT_SUSPENDED,