add missing thread_tick in the !DO_PSTATS case

panda/src/pstatclient/pStatClient.h

@@ -251,6 +251,7 @@ PUBLISHED:
   INLINE static void resume_after_pause() { }
 
   static void main_tick() { }
+  static void thread_tick(const string &) { }
 };
 
 #endif  // DO_PSTATS