ui: Convert vnc_display_init(), init_keyboard_layout() to Error

Signed-off-by: Fei Li <fli@suse.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20181017082702.5581-27-armbru@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
6 files changed