Merge remote-tracking branch 'remotes/kraxel/tags/ui-20180202-pull-request' into staging

ui: use QIONetListener in vnc, bugfixes for sdl1 and vnc.

# gpg: Signature made Fri 02 Feb 2018 07:17:36 GMT
# gpg:                using RSA key 4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/ui-20180202-pull-request:
  ui: correctly advance output buffer when writing SASL data
  ui: convert VNC server to QIONetListener
  ui: fix mixup between qnum and qcode in SDL1 key handling

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>