Ensure that get_bloginfo( 'pingback_url' ) uses site_url(), for SSL awareness.

props technosailor.
fixes #25418.


git-svn-id: https://develop.svn.wordpress.org/trunk@25671 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/general-template.php

@@ -478,7 +478,7 @@ function get_bloginfo( $show = '', $filter = 'raw' ) {
 			$output = get_feed_link('comments_rss2');
 			break;
 		case 'pingback_url':
-			$output = get_option('siteurl') .'/xmlrpc.php';
+			$output = site_url( 'xmlrpc.php' );
 			break;
 		case 'stylesheet_url':
 			$output = get_stylesheet_uri();