meson: Fix warning building GstGLEGL
We forgot to add the GstGL
gir as a dependency which was properly
done for GstGLWayland and GstGLX11.
And document why we use a list for all_libraries
We forgot to add the GstGL
gir as a dependency which was properly
done for GstGLWayland and GstGLX11.
And document why we use a list for all_libraries