This changes default behavior when creating a sample struct
in C++ code: it is now initialized to default values. If this
ever turns out to be a performance problem, we can either add
additional constructors or use special functions that do
not initialize memory, such as make_unique_for_overwrite.
This removes non-standard (respectively >C++20) constructs,
namely designated initializers.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
