Add const and std::as_const

src/playlist/playlistbackend.cpp

@@ -21,6 +21,7 @@
 
 #include "config.h"
 
+#include <utility>
 #include <memory>
 
 #include <QObject>
@@ -307,7 +308,7 @@ PlaylistItemPtr PlaylistBackend::RestoreCueData(PlaylistItemPtr item, SharedPtr<
     }
   }
 
-  for (const Song &from_list : song_list) {
+  for (const Song &from_list : std::as_const(song_list)) {
     if (from_list.url().toEncoded() == song.url().toEncoded() && from_list.beginning_nanosec() == song.beginning_nanosec()) {
       // We found a matching section; replace the input item with a new one containing CUE metadata
       return make_shared<SongPlaylistItem>(from_list);