note 15562 added to function.printf

Be sure that the output channel is available to write on before executing printf()! Some functions in classes available from various sources (in my case, DB_Sql::query() in PHPLIB) assume that printing will work, even after the default output stream has been closed. For me the issue was most notable in PHP4 session management when I was creating my own sess_write() handler. Since I was unable to find any function that checks for the output stream that printf() uses, I just had to drop the crazy use of the printf(). (does some function already exist to check for the presence of an output stream?) http://www.php.net/manual/en/function.printf.php