Log Message:
mlterm: update to 3.8.5.

Changes noted in doc/en/ReleaseNote:

ver 3.8.5
* Support libvterm (https://launchpad.net/libvterm) compatible library partially.
* Support DRCS-Sixel.
  (See drcssixel/DRCS-SIXEL-v2 and \ 
https://qiita.com/arakiken/items/626b02cd857d20c12fbc)
* Support SDL2.
  (Build mlterm with --with-gui=sdl2 option.) (see doc/en/README.sdl2)
* Support ligature of "Fira Code" font in -otl option.
* Add --halfwidth / "unicode_half_width_areas" option.
* Add --emoji / "emoji_path" option which makes mlterm to use a \ 
specified emoji font
  (NotoColorEmoji.ttf etc) instead of image files in ~/.mlterm/emoji.
* Add vte 0.50.0 API symbols to libvte compatible library.
* Treat not only U+1F1000-1F6FF but also U+1F900-1F9FF characters as emoji.
* Drop "show_picture" and "add_frame" from OSC 5379.
* Bug fixes:
  Fix corrupt screen in showing inline pictures if "use_ot_layout" \ 
option is true.