Actually make Parser::pstPass2() private

Nothing else uses this anywhere in SVN or Git as far as I can tell

Change-Id: I0ea0ebe5d11ab50fef455dd0239912e206606cd8

includes/parser/Parser.php

@@ -4594,14 +4594,13 @@ class Parser {
 
 	/**
 	 * Pre-save transform helper function
-	 * @private
 	 *
 	 * @param $text string
 	 * @param $user User
 	 *
 	 * @return string
 	 */
-	function pstPass2( $text, $user ) {
+	private function pstPass2( $text, $user ) {
 		global $wgContLang;
 
 		# Note: This is the timestamp saved as hardcoded wikitext to