Fix implicit functions declarations

--- xcalendar/xcalendar.h
+++ xcalendar/xcalendar.h
@@ -37,6 +37,7 @@
 
 
 #include <stdio.h>
+#include <stdlib.h>
 #include  <X11/Xos.h>
 #include <X11/Xlib.h>
 #include <X11/Intrinsic.h>
--- xcalendar/lists.c
+++ xcalendar/lists.c
@@ -25,6 +25,7 @@
 
 #include "xcalendar.h"
 
+is_last(LList *list);
 
 List 
 CreateList(length, elementSize)