[BUG][PL] Levelpack-specific postview jingles no longer play

[The Tomato Watcher]

In NL CE 1.2 (and possibly earlier versions as well), if a levelpack includes its own success.ogg and failure.ogg in its root folder (which are supposed to play instead of the default jingles), they will not be played on the postview screen if postview jingles are enabled; only the default jingles located in the NeoLemmix sound folder will ever be played.