m4/gst-gl: Add dummy GST_GL_HAVE_WINDOW_WINRT
Add a dummy define to make fix the autotools build for now. To actually build WinRT support, use the meson build.
Followup for !403 (merged)
Add a dummy define to make fix the autotools build for now. To actually build WinRT support, use the meson build.
Followup for !403 (merged)