Use correct variable in atomlib library, inside an error message. props rlerdorf, see #24110.

git-svn-id: https://develop.svn.wordpress.org/trunk@24190 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/atomlib.php

@@ -131,8 +131,8 @@ class AtomParser {
 
             if(!xml_parse($parser, $data, feof($fp))) {
                 trigger_error(sprintf(__('XML error: %s at line %d')."\n",
-                    xml_error_string(xml_get_error_code($xml_parser)),
-                    xml_get_current_line_number($xml_parser)));
+                    xml_error_string(xml_get_error_code($parser)),
+                    xml_get_current_line_number($parser)));
                 $ret = false;
                 break;
             }