The display may be corrupted when changing screen colour depth in
qemu-system-ppc/MacOS since 7.0.

Do not short-cut qemu_console_resize() if the surface is backed by vga
vram. When the scanout isn't set, or it is already allocated, or opengl,
and the size is fitting, we still avoid the reallocation & replace path.

Fixes: commit cb8962c1 ("ui: do not create a surface when resizing a GL scanout")

Reported-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20220725115815.2461322-1-marcandre.lureau@redhat.com>