vga: add edid support, qxl bugfixes.

# gpg: Signature made Thu 27 Sep 2018 08:12:32 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/vga-20180927-pull-request:
  qxl: support mono cursors with inverted colors
  qxl: use guest_monitor_config for local renderer.
  display/stdvga: add edid support.
  display/edid: add DEFINE_EDID_PROPERTIES
  display/edid: add region helper.
  display/edid: add qemu_edid_size()
  display/edid: add edid generator to qemu.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>