By zero-initializing the data_ member we can make most functions
constexpr which will come in handy in upcoming patches. Note that this
is due to C++17. In C++20 we will be able to leave data_ uninitialized
for constexpr. The Matrix(std::array) version of the constructor can
not be constexpr because std::copy only became constexpr in C++20.
Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>