vl: add -vga help support
Provide help output similar to other argument help handling:
$ qemu-system-x86_64 -vga help
none
std standard VGA (default)
cirrus Cirrus VGA
vmware VMWare SVGA
xenfb
qxl QXL VGA
virtio Virtio VG
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id:
20190412152713.16018-3-marcandre.lureau@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>