Fix for libical >= 4

Index: src/calendar_notes.c
--- src/calendar_notes.c.orig
+++ src/calendar_notes.c
@@ -67,7 +67,7 @@ cal_check_notes (guint32 julian_start, guint32 julian_
 /*------------------------------------------------------------------------------*/
 
 void
-cal_notes_foreach (guint32 julian_start, guint32 julian_end, gboolean (*cnfunc)(), GUI *appGUI)
+cal_notes_foreach (guint32 julian_start, guint32 julian_end, gboolean (*cnfunc)(struct note*, GUI*), GUI *appGUI)
 {
 	GSList *node;
 	struct note *n;
