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>
diff --git a/commit.c b/commit.c
index 6d77787..ca474a7 100644
--- a/commit.c
+++ b/commit.c
@@ -266,7 +266,7 @@ const void *get_commit_buffer(const struct commit *commit, unsigned long *sizep)
 	if (!ret) {
 		enum object_type type;
 		unsigned long size;
-		ret = read_sha1_file(commit->object.oid.hash, &type, &size);
+		ret = read_object_file(&commit->object.oid, &type, &size);
 		if (!ret)
 			die("cannot read commit object %s",
 			    oid_to_hex(&commit->object.oid));
@@ -383,7 +383,7 @@ int parse_commit_gently(struct commit *item, int quiet_on_missing)
 		return -1;
 	if (item->object.parsed)
 		return 0;
-	buffer = read_sha1_file(item->object.oid.hash, &type, &size);
+	buffer = read_object_file(&item->object.oid, &type, &size);
 	if (!buffer)
 		return quiet_on_missing ? -1 :
 			error("Could not read %s",
@@ -1206,7 +1206,7 @@ static void handle_signed_tag(struct commit *parent, struct commit_extra_header
 	desc = merge_remote_util(parent);
 	if (!desc || !desc->obj)
 		return;
-	buf = read_sha1_file(desc->obj->oid.hash, &type, &size);
+	buf = read_object_file(&desc->obj->oid, &type, &size);
 	if (!buf || type != OBJ_TAG)
 		goto free_return;
 	len = parse_signature(buf, size);