[Bug c++/98933] P0784R7 example support: constexpr new

[markus.kuehni at triviso dot ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98933

--- Comment #4 from Mark <markus.kuehni at triviso dot ch> ---
So this is the only way?

```
#include <memory>

template<typename T> struct S  {
        std::size_t sz;
        T *ps;

    template<std::size_t N> 
    constexpr S(T (&p)[N]) :
                        sz { N }, ps {p} {}
};

static constexpr char buf[] {"Hello"};
constexpr S str(buf);
// str ends up pointing to a static array
// containing the string "Hello!".
```