Add several uses of get_object_hash.

Convert most instances where the sha1 member of struct object is
dereferenced to use get_object_hash.  Most instances that are passed to
functions that have versions taking struct object_id, such as
get_sha1_hex/get_oid_hex, or instances that can be trivially converted
to use struct object_id instead, are not converted.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Jeff King <peff@peff.net>

cache-tree.c

@@ -657,7 +657,7 @@ static void prime_cache_tree_rec(struct cache_tree *it, struct tree *tree)
 	struct name_entry entry;
 	int cnt;
 
-	hashcpy(it->sha1, tree->object.sha1);
+	hashcpy(it->sha1, get_object_hash(tree->object));
 	init_tree_desc(&desc, tree->buffer, tree->size);
 	cnt = 0;
 	while (tree_entry(&desc, &entry)) {