lxc: Fix virsh console doesn't work after restarting libvirtd

Because tty path is unexpectedly not saved in the live configuration
file of a domain, libvirtd cannot get the console of the domain back
after restarting.

The reason why the tty path isn't saved is that, to save the tty path,
the save function, virDomainSaveConfig, requires that the target domain
is running (pid != -1), however, lxc driver calls the function before
starting the domain to pass the configuration to controller.

To ensure to save the tty path, the patch lets lxc driver call the save
function again after starting the domain.

src/lxc/lxc_driver.c

@@ -1284,7 +1284,7 @@ static int lxcVmStart(virConnectPtr conn,
     if (lxcSetupInterfaces(conn, vm->def, &nveths, &veths) != 0)
         goto cleanup;
 
-    /* Persist the live configuration now we have veth & tty info */
+    /* Save the configuration for the controller */
     if (virDomainSaveConfig(driver->stateDir, vm->def) < 0)
         goto cleanup;
 
@@ -1328,6 +1328,13 @@ static int lxcVmStart(virConnectPtr conn,
         goto cleanup;
     }
 
+    /*
+     * Again, need to save the live configuration, because the function
+     * requires vm->def->id != -1 to save tty info surely.
+     */
+    if (virDomainSaveConfig(driver->stateDir, vm->def) < 0)
+        goto cleanup;
+
     rc = 0;
 
 cleanup: