Fail to encode attachement filenames properly.

[Jinhyok Heo <novembre+dated+1020567757.8c22a8@ournature.org>]

If I send a non-latin filename attachment, Gnus seems to fail to
encode it properly.

For example, a correct attachement mime part would start like the
following.
,--------------------------------------------
|Content-Type: application/octet-stream;
|        name="=?euc-kr?B?tOuxuLGztbW80ijAzrHHwKew+LmuKS5od3A=?="
|Content-Transfer-Encoding: base64
|Content-Disposition: attachment;
|        filename="=?euc-kr?B?tOuxuLGztbW80ijAzrHHwKew+LmuKS5od3A=?="
`--------------------------------------------

But my Gnus which I got it from cvs recently makes mime parts like
,--------------------------------------------
|Content-Type: application/octet-stream
|Content-Disposition: attachment;
|  filename*=euc-kr''kin_%bc%b3%b9%ae%c1%f6.hwp
|Content-Transfer-Encoding: base64
`--------------------------------------------

Gnus seems to fail to encode filenames correctly.

-- 
| Jinhyok Heo (novembre @ ournature.org || http://ournature.org/~novembre/)
|--------------------------------------------------------------------------
| "We are still reaching for the sky. In the developed countries people
|  are coming back down, saying, `It's empty up there.'" --- a Ladakhi monk