tmp-objdir: stop using the_repository

Stop using `the_repository` in the "tmp-objdir" subsystem by passing
in the repostiroy when creating a new temporary object directory.

While we could trivially update the caller to pass in the hash algorithm
used by the index itself, we instead pass in `the_hash_algo`. This is
mostly done to stay consistent with the rest of the code in that file,
which isn't prepared to handle arbitrary repositories, either.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

bulk-checkin.c

@@ -333,7 +333,7 @@ void prepare_loose_object_bulk_checkin(void)
 	if (!odb_transaction_nesting || bulk_fsync_objdir)
 		return;
 
-	bulk_fsync_objdir = tmp_objdir_create("bulk-fsync");
+	bulk_fsync_objdir = tmp_objdir_create(the_repository, "bulk-fsync");
 	if (bulk_fsync_objdir)
 		tmp_objdir_replace_primary_odb(bulk_fsync_objdir, 0);
 }