ui: better unicode support for curses, v2.

# gpg: Signature made Wed 13 Mar 2019 07:29:44 GMT
# gpg:                using RSA key 4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>" [full]
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>" [full]
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>" [full]
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/ui-20190313-pull-request:
  curses: add option to specify VGA font encoding
  iconv: detect and make curses depend on it
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>