Sync LED state when gaining focus

The state might have changed when we didn't have focus. Get
everything back in sync once we're back in control.
diff --git a/vncviewer/Viewport.h b/vncviewer/Viewport.h
index 652feb4..31158c2 100644
--- a/vncviewer/Viewport.h
+++ b/vncviewer/Viewport.h
@@ -49,6 +49,8 @@
 
   // Change client LED state
   void setLEDState(unsigned int state);
+  // Change server LED state
+  void pushLEDState();
 
   void draw(Surface* dst);