remove iOS flicker

PanoPainter/GameViewController.m

@@ -468,17 +468,17 @@ std::set<UITouch*> ignored_touch;
 
         App::I.tick(dt.count());
 
+        [self async_lock];
         if (!(App::I.redraw || App::I.animate || !working_list.empty()))
         {
             //[self.context presentRenderbuffer:GL_FRAMEBUFFER];
-            //[self async_unlock];
-            //[self->glview display];
+            [self->glview display];
+            [self async_unlock];
             std::unique_lock<std::mutex> lock(render_mutex);
             render_cv.wait(lock);
             continue;
         }
 
-        [self async_lock];
         while (!working_list.empty())
         {
             working_list.front()();