ui/console: message surface tweaks.
ui/cocoa: bugfixes and cleanups.

# gpg: Signature made Thu 04 Mar 2021 08:36:53 GMT
# gpg:                using RSA key A0328CFFB93A17A79901FE7D4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>" [full]
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>" [full]
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>" [full]
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/ui-20210304-pull-request:
  virtio-gpu: Do not distinguish the primary console
  ui/console: Pass placeholder surface to displays
  ui/console: Add placeholder flag to message surface
  ui/cocoa: Replace fprintf with error_report
  configure: Improve OpenGL dependency detections
  ui/cocoa: Fix stride resolution of pixman image
  ui/gtk: vte: fix sending multiple characeters
  ui/cocoa: Remove the uses of full screen APIs

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