Remove get_object_hash.

Convert all instances of get_object_hash to use an appropriate reference
to the hash member of the oid member of struct object.  This provides no
functional change, as it is essentially a macro substitution.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Jeff King <peff@peff.net>
diff --git a/builtin/commit.c b/builtin/commit.c
index 795f9d2..6aac5e2 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -299,7 +299,7 @@
 	opts.dst_index = &the_index;
 
 	opts.fn = oneway_merge;
-	tree = parse_tree_indirect(get_object_hash(current_head->object));
+	tree = parse_tree_indirect(current_head->object.oid.hash);
 	if (!tree)
 		die(_("failed to unpack HEAD tree object"));
 	parse_tree(tree);
@@ -1766,7 +1766,7 @@
 	if (!transaction ||
 	    ref_transaction_update(transaction, "HEAD", sha1,
 				   current_head
-				   ? get_object_hash(current_head->object) : null_sha1,
+				   ? current_head->object.oid.hash : null_sha1,
 				   0, sb.buf, &err) ||
 	    ref_transaction_commit(transaction, &err)) {
 		rollback_index_files();
@@ -1793,10 +1793,10 @@
 		cfg = init_copy_notes_for_rewrite("amend");
 		if (cfg) {
 			/* we are amending, so current_head is not NULL */
-			copy_note_for_rewrite(cfg, get_object_hash(current_head->object), sha1);
+			copy_note_for_rewrite(cfg, current_head->object.oid.hash, sha1);
 			finish_copy_notes_for_rewrite(cfg, "Notes added by 'git commit --amend'");
 		}
-		run_rewrite_hook(get_object_hash(current_head->object), sha1);
+		run_rewrite_hook(current_head->object.oid.hash, sha1);
 	}
 	if (!quiet)
 		print_summary(prefix, sha1, !current_head);