Merge remote-tracking branch 'remotes/kraxel/tags/ui-20180518-pull-request' into...

Merge remote-tracking branch 'remotes/kraxel/tags/ui-20180518-pull-request' into staging

ui: bugfixes, move x11 dependency to modules.

# gpg: Signature made Fri 18 May 2018 08:40:41 BST
# 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-20180518-pull-request:
  sdl: Move use of surface pointer below check for whether it is NULL
  ui: add x_keymap.o to modules
  console: Avoid segfault in screendump

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