glthread: disable glthread if the context is lost

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14000>

src/mesa/main/glthread.c

@@ -191,8 +191,13 @@ _mesa_glthread_flush_batch(struct gl_context *ctx)
    if (!glthread->enabled)
       return;
 
-   if (!glthread->used)
+   if (ctx->CurrentServerDispatch == ctx->ContextLost) {
+      _mesa_glthread_destroy(ctx, "context lost");
       return;
+   }
+
+   if (!glthread->used)
+      return; /* the batch is empty */
 
    /* Pin threads regularly to the same Zen CCX that the main thread is
     * running on. The main thread can move between CCXs.