Provide access to the base threadpool classes

unsupported/Eigen/CXX11/src/Tensor/TensorDeviceThreadPool.h

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorDeviceThreadPool.h b/unsupported/Eigen/CXX11/src/Tensor/TensorDeviceThreadPool.h
index fc03d84..c028914 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorDeviceThreadPool.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorDeviceThreadPool.h
@@ -15,8 +15,10 @@
 // Use the SimpleThreadPool by default. We'll switch to the new non blocking
 // thread pool later.
 #ifdef EIGEN_USE_NONBLOCKING_THREAD_POOL
+template <typename Env> using ThreadPoolTempl = NonBlockingThreadPoolTempl<Env>;
 typedef NonBlockingThreadPool ThreadPool;
 #else
+template <typename Env> using ThreadPoolTempl = SimpleThreadPoolTempl<Env>;
 typedef SimpleThreadPool ThreadPool;
 #endif