attach jni to ui thread, fix bucket bounding box

src/app.cpp

@@ -15,6 +15,8 @@
 void android_async_lock(struct engine* engine);
 void android_async_swap(struct engine* engine);
 void android_async_unlock(struct engine* engine);
+void android_attach_jni();
+void android_detach_jni();
 #elif _WIN32
 bool async_lock_try();
 void async_lock();
@@ -853,6 +855,10 @@ void App::ui_thread_main()
     ui_thread_id = std::this_thread::get_id();
     ui_running = true;
 
+#if __ANDROID__
+    android_attach_jni();
+#endif
+
     init();
 
     auto t_start = std::chrono::high_resolution_clock::now();
@@ -922,6 +928,9 @@ void App::ui_thread_main()
             rendered_frames++;
         }
     }
+#if __ANDROID__
+    android_detach_jni();
+#endif
 }
 
 void App::render_thread_start()