That's what Windows do apparently. Anything with more than 4GiB of VRAM
would report less otherwise, confusing the VRAM detection in some games.

The Mafia III launcher is trying to open a warning popup with a 8GiB
VRAM GPU for instance, as the reported value overflows to 0.
Signed-off-by: Rémi Bernon <rbernon@codeweavers.com>
Signed-off-by: Hans Leidekker <hans@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>