Fix wp_basename() for Windows by replacing %5C with /.

Props SergeyBiryukov
fixes #22138


git-svn-id: http://core.svn.wordpress.org/trunk@22310 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/formatting.php

@@ -3249,7 +3249,7 @@ function sanitize_text_field($str) {
  * @return string
  */
 function wp_basename( $path, $suffix = '' ) {
-	return urldecode( basename( str_replace( '%2F', '/', urlencode( $path ) ), $suffix ) );
+	return urldecode( basename( str_replace( array( '%2F', '%5C' ), '/', urlencode( $path ) ), $suffix ) );
 }
 
 /**