Don't attempt to vectorize mean reductions of integers since we can't use
SSE or AVX instructions to divide 2 integers.

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

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h b/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h
index 34ba4e3..f94ffa0 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h
@@ -93,7 +93,7 @@
 
 template <typename T> struct MeanReducer
 {
-  static const bool PacketAccess = true;
+  static const bool PacketAccess = !NumTraits<T>::IsInteger;
   static const bool IsStateful = true;
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE