message: Improve error message when we have an error code
diff: @@ -38,7 +38,7 @@ namespace vcpkg
  const std::error_code& error() const { return m_err; }
  std::error_code& error() { return m_err; }
  - CStringView to_string() const { return "value was error"; }
  + CStringView to_string() const { return m_err.message(); }
  private:
  std::error_code m_err;
  