Use typedef pointer for static_cast

Author: EricaCMitchell

src/TiledArray/tensor/tensor.h

@@ -188,7 +188,7 @@ class Tensor {
 #if EIGEN_HAS_MAJOR_VERSION_5
     // Eigen 3.5.x returns nullptr if size=0
     auto* ptr = (!size && range_.rank())
-                    ? static_cast<allocator_type::pointer>(std::malloc(size))
+                    ? static_cast<pointer>(std::malloc(size))
                     : allocator.allocate(size);
 #else
     auto* ptr = allocator.allocate(size);