tree: convert parse_tree_indirect to struct object_id

Convert parse_tree_indirect to take a pointer to struct object_id.
Update all the callers.  This transformation was achieved using the
following semantic patch and manual updates to the declaration and
definition.  Update builtin/checkout.c manually as well, since it uses a
ternary expression not handled by the semantic patch.

@@
expression E1;
@@
- parse_tree_indirect(E1.hash)
+ parse_tree_indirect(&E1)

@@
expression E1;
@@
- parse_tree_indirect(E1->hash)
+ parse_tree_indirect(E1)

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit.c

@@ -313,7 +313,7 @@ static void create_base_index(const struct commit *current_head)
 	opts.dst_index = &the_index;
 
 	opts.fn = oneway_merge;
-	tree = parse_tree_indirect(current_head->object.oid.hash);
+	tree = parse_tree_indirect(&current_head->object.oid);
 	if (!tree)
 		die(_("failed to unpack HEAD tree object"));
 	parse_tree(tree);