Fix reverse iterators xstorage (#2908)

# Checklist

- [ ] The title and commit message(s) are descriptive.
- [ ] Small commits made to fix your PR have been squashed to avoid
history pollution.
- [ ] Tests have been added for new features or bug fixes.
- [ ] API of new functions and classes are documented.

# Description

<!---
Give any relevant description here.
If your PR fixes an issue, please include "Fixes #ISSUE" (substituting
the relevant issue ID).
-->

---------

Co-authored-by: Alexis Placet <2400067+Alex-PLACET@users.noreply.github.com>

Author: Alex-PLACET

include/xtensor/containers/xstorage.hpp

@@ -1640,6 +1640,16 @@ namespace xt
             return m_array.cend();
         }
 
+        auto crbegin() const
+        {
+            return m_array.crbegin();
+        }
+
+        auto crend() const
+        {
+            return m_array.crend();
+        }
+
         constexpr std::size_t operator[](std::size_t idx) const
         {
             return m_array[idx];

test/test_xfixed.cpp

@@ -22,6 +22,7 @@
 #include "xtensor/core/xnoalias.hpp"
 #include "xtensor/io/xio.hpp"
 #include "xtensor/misc/xmanipulation.hpp"
+#include "xtensor/views/xview.hpp"
 
 #include "test_common_macros.hpp"
 
@@ -306,6 +307,13 @@ namespace xt
         using tiny_tensor = xtensor_fixed<double, xshape<2>, layout_type::row_major, false>;
         EXPECT_GT(sizeof(fixed_tensor), sizeof(tiny_tensor));
     }
+
+    TEST(xtensor_fixed, iterators)
+    {
+        auto arr = xt::xtensor<double, 1>({5, 5, 5, 5, 5});
+        auto fixed_arr = xt::xtensor_fixed<double, xt::xshape<3>>{1, 2, 3};
+        xt::view(arr, xt::range(0, 3)) = fixed_arr + 1;
+    }
 }
 
 #endif