A moving constructor from a matrix with arbitrary implementing type and policy but same types of elements and an allocator.
| Derived2 | is a type which is based on the moved matrix. |
| Policy2 | is an execution policy of the matrix being moved. |
| r | is an rvalue reference to the matrix being moved into the constructed one. The matrix must have the same type of its elements (i.e. value_type) and allocator (allocator_type). |