start to impliment mscp as a library

this commit starts to refactor file.h|c to path.h|c and
add mscp.c|h. not completed yet.

src/list.h

@@ -208,6 +208,32 @@ static inline void list_splice(struct list_head *list, struct list_head *head)
 		__list_splice(list, head);
 }
 
+static inline void __list_splice_tail(struct list_head *list,
+				      struct list_head *head)
+{
+	struct list_head *first = list->next;
+	struct list_head *last = list->prev;
+	struct list_head *at = head->prev;
+
+	first->prev = at;
+	at->next = first;
+
+	last->next = head;
+	at->prev = last;
+}
+
+/**
+ * list_splice_tail - join two lists
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ */
+static inline void list_splice_tail(struct list_head *list, struct list_head *head)
+{
+	if (!list_empty(list))
+		__list_splice_tail(list, head);
+}
+
+
 /**
  * list_splice_init - join two lists and reinitialise the emptied list.
  * @list: the new list to add.