ui: highres logo for sdl and gtk, bugfixes for vnc and egl.

# gpg: Signature made Mon 21 Jan 2019 14:11:39 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-20190121-pull-request:
  egl-helpers.h: do not depend on X11 Window type, use EGLNativeWindowType
  vnc: detect and optimize pageflips
  sdl: add support for high resolution window icon
  ui: fix icon display for GTK frontend under GNOME Shell with Wayland
  ui: install logo icons to $prefix/share/icons

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