Merge remote-tracking branch 'remotes/kraxel/tags/ui-20180222-pull-request' into staging

ui: reverse keymap improvements.
sdl2: hotkey fix.
opengl: dmabuf fixes.

# gpg: Signature made Thu 22 Feb 2018 10:22:58 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-20180222-pull-request:
  keymap: consider modifier state when picking a mapping
  keymap: record multiple keysym -> keycode mappings
  keymap: numpad keysyms and keycodes are fixed
  keymap: use glib hash for kbd_layout_t
  keymap: make struct kbd_layout_t private to ui/keymaps.c
  egl-helpers: add alpha channel to texture format
  egl-headless: cursor_dmabuf: handle NULL cursor
  console/opengl: split up dpy_gl_cursor ops
  sdl2: fix hotkey keyup

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