Add a winsys for code paths common to the libgl-gdi and
libgl-d3d12 targets when using the D3D12 gallium driver.
Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Reviewed-by: Charmaine Lee <charmainel@vmware.com>
Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7535>
Louis-Francis Ratté-Boulianne