commit: use DEFINE_LIST_SORT

Use DEFINE_LIST_SORT to build a typed sort function for commit_list
entries instead of calling llist_mergesort().  This gets rid of the next
pointer accessor functions and their calling overhead at the cost of a
slightly increased object text size.

Before:
__TEXT	__DATA	__OBJC	others	dec	hex
18795	92	0	104654	123541	1e295	commit.o

With this patch:
__TEXT	__DATA	__OBJC	others	dec	hex
18963	92	0	106094	125149	1e8dd	commit.o

Signed-off-by: René Scharfe <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: rscharfe

commit.c

@@ -631,31 +631,23 @@ struct commit_list * commit_list_insert_by_date(struct commit *item, struct comm
 	return commit_list_insert(item, pp);
 }
 
-static int commit_list_compare_by_date(const void *a, const void *b)
+static int commit_list_compare_by_date(const struct commit_list *a,
+				       const struct commit_list *b)
 {
-	timestamp_t a_date = ((const struct commit_list *)a)->item->date;
-	timestamp_t b_date = ((const struct commit_list *)b)->item->date;
+	timestamp_t a_date = a->item->date;
+	timestamp_t b_date = b->item->date;
 	if (a_date < b_date)
 		return 1;
 	if (a_date > b_date)
 		return -1;
 	return 0;
 }
 
-static void *commit_list_get_next(const void *a)
-{
-	return ((const struct commit_list *)a)->next;
-}
-
-static void commit_list_set_next(void *a, void *next)
-{
-	((struct commit_list *)a)->next = next;
-}
+DEFINE_LIST_SORT(static, commit_list_sort, struct commit_list, next);
 
 void commit_list_sort_by_date(struct commit_list **list)
 {
-	*list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
-				commit_list_compare_by_date);
+	commit_list_sort(list, commit_list_compare_by_date);
 }
 
 struct commit *pop_most_recent_commit(struct commit_list **list,