libxl: copy persistent domain definition while starting a guest

We should make a copy of current definition to preserve a persistent
definition, because we later update the definition with live changes.
The live definition is discarded on domain shutdown and replaced by the
copy we make before starting the domain.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

src/libxl/libxl_domain.c

@@ -959,6 +959,10 @@ libxlDomainStart(libxlDriverPrivatePtr driver, virDomainObjPtr vm,
         VIR_FREE(managed_save_path);
     }
 
+    if (virDomainObjSetDefTransient(cfg->caps, driver->xmlopt,
+                                    vm, true) < 0)
+        goto cleanup;
+
     if (libxlBuildDomainConfig(driver->reservedGraphicsPorts, vm->def,
                                cfg->ctx, &d_config) < 0)
         goto cleanup;