(PHP 4 >= 4.0.7, PHP 5)
mcrypt_generic_deinit — This function deinitializes an encryption module
$td
   )
   This function terminates encryption specified by the encryption
   descriptor (td). It clears all buffers, but does
   not close the module.  You need to call
   mcrypt_module_close() yourself. (But PHP does this for
   you at the end of the script.)
  
td
     The encryption descriptor.
   成功时返回 TRUE, 或者在失败时返回 FALSE.