Remove CXX11/ directory nesting for Tensor modules

libeigen/eigen!2199

Co-authored-by: Rasmus Munk Larsen <rmlarsen@gmail.com>

unsupported/Eigen/src/TensorUtil/CXX11Meta.h

@@ -0,0 +1,18 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2013 Christian Seiler <christian@iwakd.de>
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef EIGEN_CXX11META_H
+#define EIGEN_CXX11META_H
+
+#include <vector>
+#include "../../../../Eigen/src/Core/util/EmulateArray.h"
+
+#include "CXX11Workarounds.h"
+
+#endif  // EIGEN_CXX11META_H

unsupported/Eigen/src/TensorUtil/CXX11Workarounds.h

@@ -0,0 +1,41 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2013 Christian Seiler <christian@iwakd.de>
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef EIGEN_CXX11WORKAROUNDS_H
+#define EIGEN_CXX11WORKAROUNDS_H
+
+namespace Eigen {
+
+namespace internal {
+
+/* array_get overloads for std::vector, used by tensor code.
+ */
+
+template <std::size_t I_, class T>
+constexpr T& array_get(std::vector<T>& a) {
+  return a[I_];
+}
+template <std::size_t I_, class T>
+constexpr T&& array_get(std::vector<T>&& a) {
+  return a[I_];
+}
+template <std::size_t I_, class T>
+constexpr T const& array_get(std::vector<T> const& a) {
+  return a[I_];
+}
+
+}  // end namespace internal
+
+}  // end namespace Eigen
+
+#endif  // EIGEN_CXX11WORKAROUNDS_H
+
+/*
+ * kate: space-indent on; indent-width 2; mixedindent off; indent-mode cstyle;
+ */