emacs-unicode-2: `read-file-name' doesn't complete chinese dir names

[Zhang Wei]

Make some chinese directory names in /tmp, eval:

(read-file-name "input" "/tmp/" "/tmp/")

and press <TAB> <TAB>, the chinese directory names are listed
with out any problem.

but eval:

(read-file-name "input" "/tmp/" "/tmp/" nil nil 'file-directory-p)

and press <TAB> <TAB>, this time the chinese directory names are
not listed any more.

============================================================
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In GNU Emacs 23.0.0.1 (i386-mingw-nt5.1.2600)
 of 2006-11-09 on THU-2B8051EF1B3
X server distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.2)'

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: CHS
  locale-coding-system: cp936
  default-enable-multibyte-characters: t

Major mode: Group

Minor modes in effect:
  gnus-topic-mode: t
  gnus-undo-mode: t
  display-time-mode: t
  show-paren-mode: t
  delete-selection-mode: t
  pc-selection-mode: t
  shell-dirtrack-mode: t
  encoded-kbd-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<return> <help-echo> g <return> d d d d q <return> 
<return> q <return> <return> q <return> d d q g <return> 
<return> q <return> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <return> 
q g C-x C-b <return> M-x r e p o r t - e m c s <backspace> 
<backspace> a c s - b u g <return> C-g C-x C-b <down> 
<return> M-< C-k C-y C-x b <return> M-x r e p r o t 
<backspace> <backspace> <backspace> o r t - e m <tab> 
<return>

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