vo_gpu: context_glx: Add X11 native resource

Surprisingly, we've managed to get this far without context_glx ever
adding the X11 display as a native resource. But with the recent change
to attempt to enable vdpau when using EGL, the hwdec now requires the
display to be added. So let's add it.

video/out/opengl/context_glx.c

@@ -339,6 +339,8 @@ static bool glx_init(struct ra_ctx *ctx)
     if (!ra_gl_ctx_init(ctx, gl, params))
         goto uninit;
 
+    ra_add_native_resource(ctx->ra, "x11", vo->x11->display);
+
     return true;
 
 uninit: