Log Message:
Update mlterm to 3.8.0.

Changes noted in doc/en/ReleaseNote:

ver 3.8.0
* Refactor source code and directory tree.
* Add "ssh_auto_reconnect" / --rcn option which enables automatic \ 
reconnecting to
  ssh server in unexpected disconnection.
* Support libssh2 on Android.
* Add "start_with_local_pty" / --slp option which disables ssh \ 
connection dialog
  on startup on Android.
* Support context menu (copy&paste, configuration etc) by long click on Android.
* Change library names.
  libmkf => libmef, libkik => libpobl
  libmlterm_core => libmlterm_coreotf (if open type layout is supported)
* Add --vsep=N and --hsep=N options (which split screen vertically or horizontally)
  to mlclientx.
* libvte compatible library supports vte 0.40.0 or later.
* Bug fixes:
  Fix the bug which 'mlcc exec hsplit [columns]' split screen by [columns - 1].
  Fix the bug which disables dynamic change of options related to ctl such as
  "bidi_mode" or etc. (Enbugged at 3.6.2)
  Fix the bug which disabled "ButtonN" shortcut key if num_lock is on.
  Fix segfault in resizing columns or rows on Android.
  Fix the default value of termios.c_cc[VSTATUS]. (Thanks to Oshima Yasushi san)