qemu: checkpoint: Allow checkpoint redefine for offline VMs

Skip the liveness and capability checks when redefining checkpoints as
we don't need qemu interactions to update the metadata.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

src/qemu/qemu_checkpoint.c

@@ -647,16 +647,18 @@ qemuCheckpointCreateXML(virDomainPtr domain,
         update_current = false;
     }
 
-    if (!virDomainObjIsActive(vm)) {
-        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                       _("cannot create checkpoint for inactive domain"));
-        return NULL;
-    }
+    if (!redefine) {
+        if (!virDomainObjIsActive(vm)) {
+            virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                           _("cannot create checkpoint for inactive domain"));
+            return NULL;
+        }
 
-    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_INCREMENTAL_BACKUP)) {
-        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                       _("incremental backup is not supported yet"));
-        return NULL;
+        if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_INCREMENTAL_BACKUP)) {
+            virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                           _("incremental backup is not supported yet"));
+            return NULL;
+        }
     }
 
     if (!(def = virDomainCheckpointDefParseString(xmlDesc, driver->xmlopt,