oneliner to fix psz_arturl check in album_art stuff

src/playlist/engine.c

@@ -534,7 +534,7 @@ void playlist_PreparseLoop( playlist_preparse_t *p_obj )
             }
             /* We already have all needed meta, but we need art right now */
             else if( p_playlist->p_fetcher->i_art_policy == ALBUM_ART_ALL &&
-                     !psz_arturl ? 1 :
+                     psz_arturl &&
                         strncmp( psz_arturl, "file://", strlen("file://") ) )
             {
                 preparse_item_t p;