Merge remote-tracking branch 'remotes/kraxel/tags/ui-20171117-pull-request' into...

sdl2 fixes for 2.11

# gpg: Signature made Fri 17 Nov 2017 10:06:27 GMT
# gpg:                using RSA key 0x4CB6D8EED3E87138
# 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-20171117-pull-request:
  sdl2: Fix broken display updating after the window is hidden
  sdl2: Do not leave grab when fullscreen
  sdl2: Fix dead keyboard after fullsceen
  sdl2: Use the same pointer show/hide logic for absolute and relative mode
  sdl2: Do not quit the emulator when an auxilliary window is closed

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