update headers

ios/include/utils/JobSystem.h

@@ -303,6 +303,8 @@ public:
         return mParallelSplitCount;
     }
 
+    size_t getThreadCount() const { return mThreadCount; }
+
 private:
     // this is just to avoid using std::default_random_engine, since we're in a public header.
     class default_random_engine {