qemu_process: don't probe iothreads if it's not supported by QEMU

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1430258Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

src/qemu/qemu_process.c

@@ -2098,6 +2098,11 @@ qemuProcessDetectIOThreadPIDs(virQEMUDriverPtr driver,
     int ret = -1;
     size_t i;
 
+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_OBJECT_IOTHREAD)) {
+        ret = 0;
+        goto cleanup;
+    }
+
     /* Get the list of IOThreads from qemu */
     if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
         goto cleanup;