details: https://anonhg.NetBSD.org/src/rev/12b6ecf11790 branches: trunk changeset: 761022:12b6ecf11790 user: haad <haad%NetBSD.org@localhost> date: Tue Jan 18 23:03:29 2011 +0000 description: bus.h is required for build so add some empty file for now.