bug #3123433 [interface] Avoid double escaping of MySQL errors.

The PMA_DBI_getError function already does escaping, so there is no need
to escape that string again on displaying.

libraries/common.lib.php

@@ -617,7 +617,6 @@ function PMA_mysqlDie($error_message = '', $the_query = '',
     } // end if
 
     if (!empty($error_message)) {
-        $error_message = htmlspecialchars($error_message);
         $error_message = preg_replace("@((\015\012)|(\015)|(\012)){3,}@", "\n\n", $error_message);
     }
     // modified to show the help on error-returns