drop debug printf

Index: src/playlist3.c
--- src/playlist3.c.orig
+++ src/playlist3.c
@@ -1492,7 +1492,6 @@ static void playlist_zoom_level_changed(void)
 {
     gboolean st_shown;
     GtkWidget *pl3_win = playlist3_get_window();
-    printf("playlist3 zoom level changed\n");
 
     if (pl3_old_zoom <= PLAYLIST_SMALL)
     {
