wined3d: Support wined3d_texture_get_dc() on WINED3DFMT_B4G4R4A4_UNORM and WINED3DFMT_B4G4R4X4_UNORM textures.
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>