message: std::random_shuffle is removed in current standard
  use <random> 's generator and std::shuffle instead
diff: #include <algorithm>
  #include <limits>
  +// std::random_shuffle is deprecated in c++14, is removed in c++17.
  +# if defined(__cplusplus) && (__cplusplus >= 201402L)
  +# include <random>
  +# define PUGIXML_SHUFFLE(rng) std::shuffle(rng.begin(), rng.end(), std::default_random_engine{std::random_device{}()})
  +# else
  +# define PUGIXML_SHUFFLE(rng) std::random_shuffle(rng.begin(), rng.end())
  +#endif
  +
  using namespace pugi;
  static void load_document_copy(xml_document& doc, const char_t* text)
  @@ -155,7 +163,7 @@ TEST(xpath_sort_random_medium)
  xpath_node_set ns = doc.select_nodes(STR("//node() | //@*"));
  std::vector<xpath_node> nsv(ns.begin(), ns.end());
  - std::random_shuffle(nsv.begin(), nsv.end());
  + PUGIXML_SHUFFLE(nsv);
  xpath_node_set copy(&nsv[0], &nsv[0] + nsv.size());
  copy.sort();
  @@ -184,7 +192,7 @@ TEST(xpath_sort_random_large)
  xpath_node_set ns = doc.select_nodes(STR("//node() | //@*"));
  std::vector<xpath_node> nsv(ns.begin(), ns.end());
  - std::random_shuffle(nsv.begin(), nsv.end());
  + PUGIXML_SHUFFLE(nsv);
  xpath_node_set copy(&nsv[0], &nsv[0] + nsv.size());
  copy.sort();
  