message: Add default constructor to Optional<T>
diff: @@ -15,6 +15,8 @@ namespace vcpkg
  class Optional
  {
  public:
  + constexpr Optional() : m_is_present(false), m_t() { }
  +
  // Constructors are intentionally implicit
  constexpr Optional(NullOpt) : m_is_present(false), m_t() { }
  