packfile: use DEFINE_LIST_SORT

Build a typed sort function for packed_git lists using DEFINE_LIST_SORT
instead of calling llist_mergesort().  This gets rid of the next pointer
accessor functions and their calling overhead at the cost of slightly
increased object text size.

Before:
__TEXT	__DATA	__OBJC	others	dec	hex
20218	320	0	110936	131474	20192	packfile.o

With this patch:
__TEXT	__DATA	__OBJC	others	dec	hex
20430	320	0	112619	133369	208f9	packfile.o

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

Author: rscharfe

packfile.c

@@ -926,20 +926,10 @@ unsigned long repo_approximate_object_count(struct repository *r)
 	return r->objects->approximate_object_count;
 }
 
-static void *get_next_packed_git(const void *p)
-{
-	return ((const struct packed_git *)p)->next;
-}
-
-static void set_next_packed_git(void *p, void *next)
-{
-	((struct packed_git *)p)->next = next;
-}
+DEFINE_LIST_SORT(static, sort_packs, struct packed_git, next);
 
-static int sort_pack(const void *a_, const void *b_)
+static int sort_pack(const struct packed_git *a, const struct packed_git *b)
 {
-	const struct packed_git *a = a_;
-	const struct packed_git *b = b_;
 	int st;
 
 	/*
@@ -966,9 +956,7 @@ static int sort_pack(const void *a_, const void *b_)
 
 static void rearrange_packed_git(struct repository *r)
 {
-	r->objects->packed_git = llist_mergesort(
-		r->objects->packed_git, get_next_packed_git,
-		set_next_packed_git, sort_pack);
+	sort_packs(&r->objects->packed_git, sort_pack);
 }
 
 static void prepare_packed_git_mru(struct repository *r)