sha1_file: convert read_sha1_file to struct object_id

Convert read_sha1_file to take a pointer to struct object_id and rename
it read_object_file.  Do the same for read_sha1_file_extended.

Convert one use in grep.c to use the new function without any other code
change, since the pointer being passed is a void pointer that is already
initialized with a pointer to struct object_id.  Update the declaration
and definitions of the modified functions, and apply the following
semantic patch to convert the remaining callers:

@@
expression E1, E2, E3;
@@
- read_sha1_file(E1.hash, E2, E3)
+ read_object_file(&E1, E2, E3)

@@
expression E1, E2, E3;
@@
- read_sha1_file(E1->hash, E2, E3)
+ read_object_file(E1, E2, E3)

@@
expression E1, E2, E3, E4;
@@
- read_sha1_file_extended(E1.hash, E2, E3, E4)
+ read_object_file_extended(&E1, E2, E3, E4)

@@
expression E1, E2, E3, E4;
@@
- read_sha1_file_extended(E1->hash, E2, E3, E4)
+ read_object_file_extended(E1, E2, E3, E4)

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

builtin/merge-tree.c

@@ -60,7 +60,7 @@ static void *result(struct merge_list *entry, unsigned long *size)
 	const char *path = entry->path;
 
 	if (!entry->stage)
-		return read_sha1_file(entry->blob->object.oid.hash, &type, size);
+		return read_object_file(&entry->blob->object.oid, &type, size);
 	base = NULL;
 	if (entry->stage == 1) {
 		base = entry->blob;
@@ -82,7 +82,8 @@ static void *origin(struct merge_list *entry, unsigned long *size)
 	enum object_type type;
 	while (entry) {
 		if (entry->stage == 2)
-			return read_sha1_file(entry->blob->object.oid.hash, &type, size);
+			return read_object_file(&entry->blob->object.oid,
+						&type, size);
 		entry = entry->link;
 	}
 	return NULL;