demos: Properly destroy command pool in cube demo
diff --git a/demos/cube.c b/demos/cube.c
index 7106266..9f4ed4c 100644
--- a/demos/cube.c
+++ b/demos/cube.c
@@ -1909,6 +1909,7 @@
         vkDestroyImageView(demo->device, demo->buffers[i].view);
         vkFreeCommandBuffers(demo->device, demo->cmd_pool, 1, &demo->buffers[i].cmd);
     }
+    vkDestroyCommandPool(demo->device, demo->cmd_pool);
     free(demo->buffers);
 
     vkDestroyCommandPool(demo->device, demo->cmd_pool);