gpu_ctx_gl: synchronize the config dimensions with the glcontext (swapchain) dimensions
gpu_ctx_gl: synchronize the config dimensions with the glcontext (swapchain) dimensions

This will be useful later on to rely on ngl_config.{width,height}
instead of glcontext.{width,height}.

gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl