Add transaction ticket to LinksUpdateComplete hook

This lets callers use commitAndWaitForReplication() more easily.

Change-Id: I743bd1f989b8fb3b7ba3e5cc8ce1bb44c00f99af

docs/hooks.txt

@@ -1974,6 +1974,7 @@ $insertions: an array of links to insert
 'LinksUpdateComplete': At the end of LinksUpdate::doUpdate() when updating,
 including delete and insert, has completed for all link tables
 &$linksUpdate: the LinksUpdate object
+$ticket: prior result of LBFactory::getEmptyTransactionTicket()
 
 'LinksUpdateConstructed': At the end of LinksUpdate() is construction.
 &$linksUpdate: the LinksUpdate object

includes/deferred/LinksUpdate.php

@@ -176,7 +176,7 @@ class LinksUpdate extends DataUpdate implements EnqueueableDataUpdate {
 		// Run post-commit hooks without DBO_TRX
 		$this->getDB()->onTransactionIdle(
 			function () {
-				Hooks::run( 'LinksUpdateComplete', [ &$this ] );
+				Hooks::run( 'LinksUpdateComplete', [ &$this, $this->ticket ] );
 			},
 			__METHOD__
 		);