list: add static initializer macro

include/vlc_list.h

@@ -45,6 +45,11 @@ struct vlc_list
     struct vlc_list *next;
 };
 
+/**
+ * Static initializer for a list head.
+ */
+#define VLC_LIST_INITIALIZER(h) { h, h }
+
 /**
  * Initializes an empty list head.
  */