Clean up the Tensor header and get rid of the EIGEN_SLEEP macro.

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

@@ -83,7 +83,7 @@ static void initializeDeviceProp() {
       // Wait for the other thread to inititialize the properties.
       while (!m_devicePropInitialized) {
         std::atomic_thread_fence(std::memory_order_acquire);
-        EIGEN_SLEEP(1000);
+        std::this_thread::sleep_for(std::chrono::milliseconds(1000));
       }
     }
   }