Use mt19937 random number generator instad of the default one

src/sort_playlist.cpp

@@ -197,7 +197,7 @@ void SortPlaylistDialog::sort() const
 	quick_sort = [this, &song_cmp, &quick_sort, &iter_swap](Iterator first, Iterator last) {
 		if (last-first > 1)
 		{
-			Iterator pivot = first+rand()%(last-first);
+			Iterator pivot = first+Global::RNG()%(last-first);
 			iter_swap(pivot, last-1);
 			pivot = last-1;