Add minimal XSS protection to appended string

ChangeLog entry

ChangeLog

@@ -14,6 +14,7 @@ phpMyAdmin - ChangeLog
 + Patch #3506552 Contest-2: Show index information in the data dictionary
 + Patch #3510656 Contest-1: Ignoring foreign keys while dropping tables
 - Bug #3509686 Reverting sort on joined column does not work
++ New transformation: append string
 
 3.5.1.0 (not yet released)
 - bug #3510784 [edit] Limit clause ignored when sort order is remembered

libraries/transformations/text_plain__append.inc.php

@@ -17,7 +17,7 @@ function PMA_transformation_text_plain__append($buffer, $options = array(), $met
         $options[0] = '';
     }
 
-    $newtext = $buffer . $options[0];  //just append the option to the original text
+    $newtext = $buffer . htmlspecialchars($options[0]);  //just append the option to the original text
 
     return $newtext;
 }