Update uim to 1.7.3.
Based on PR 46030 by YAMASHIRO, Jun.
(enable commented out wnn4 option additionally)

Overview of changes from 1.7.2 to 1.7.3
=======================================
* Fixes
  - Qt4 bridge
    * Fix im-delete-text in QTextEdit
    * Build fix for NetBSD ([uim-ja 322])

  - uim-m17nlib
    * Don't discard key release event when input mode is off (#45734)
    * Fix crashes with some IMs (regressed in 1.7.0-alpha).

* Others
  - Generic build fix for GNU/Hurd ([uim-ja 310])

Overview of changes from 1.7.1 to 1.7.2
=======================================
* Fixes
  - libuim
    * Fix crash in im-acquire-text with selection

  - uim-pref-qt4
    * Fix build failure when --as-needed is used (#40385, Julian Taylor)

* Enhancements
  - Qt4 bridge
    * Support text acquisition API with QTextEdit

* Others
  - Plug very minor memory leak in uim-xim
  - Plug very minor file descriptor leak in libuim-custom

Overview of changes from 1.7.0 to 1.7.1
=======================================
* Fixes
  - uim-tutcode
    * Fix behavior when on-key and off-key are different

  - uim-dict-gtk
  - uim-dict-gtk3
    * Fix compilation with Canna >= 3.7

- fileio.scm
    * Fix for files with no newline at the end

* Enhancements
  - uim-byeoru
    * Speedup in conversion by change of system dictionary format
    * Introduce a new way to define a personal dictionary

  - uim-tutcode
    * Show stroke help temporarily by keys in kanji combination guide
    * Support bushu composition which consists of three or more bushu
      on auto help
    * Use bushu.help file on auto help and bushu conversion

  - uim-toolbar-gtk3-systray
  - uim-toolbar-gtk-systray
    * gnome-shell support

  - uim-notify
    * Support dynamic reconfiguration of the agent selection

* Others
  - Make uim functional when --disable-notify is set at configure

(obache)