On Windows, we don't use the low-level GBM/EGL helpers (no dmabuf etc),
we can turn on GL area support for the rest of rendering.

(fwiw, GDK backend may be either WGL or EGL)

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Tested-by: Bernhard Beschow <shentey@gmail.com>
Message-Id: <20230515132527.1026064-1-marcandre.lureau@redhat.com>