Prevent direct instantation of ThreadManager

Reviewed By: marc


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@664967 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/cpp/src/concurrency/ThreadManager.h b/lib/cpp/src/concurrency/ThreadManager.h
index a90c5d2..0383a09 100644
--- a/lib/cpp/src/concurrency/ThreadManager.h
+++ b/lib/cpp/src/concurrency/ThreadManager.h
@@ -36,9 +36,10 @@
  */
 class ThreadManager {
 
- public:
+ protected:
   ThreadManager() {}
 
+ public:
   virtual ~ThreadManager() {}
 
   /**