Cleanup includes in Tensor module after switch to C++11 and above

unsupported/Eigen/CXX11/Tensor

diff --git a/unsupported/Eigen/CXX11/Tensor b/unsupported/Eigen/CXX11/Tensor
index a110b52..6a8dc2c 100644
--- a/unsupported/Eigen/CXX11/Tensor
+++ b/unsupported/Eigen/CXX11/Tensor
@@ -83,10 +83,8 @@
   #else
     #include <cuda_runtime.h>
   #endif
-  #if __cplusplus >= 201103L
-    #include <atomic>
-    #include <unistd.h>
-  #endif
+  #include <atomic>
+  #include <unistd.h>
 #endif
 
 #include "src/Tensor/TensorMacros.h"