unbreak NFS lockers

[kaduk]

We currently only support AFS lockers, but there are still some NFS lockers in the wild. We should make them work again.

[andersk]

If you are tempted to implement this, make sure not to go enable the portmap daemon for all debathena-standard users. (I’m really not sure why anyone would be tempted to implement this, though.)

[jdreed]

To be fair, this ticket is less about NFS as it is making sure that our locker support is still as filesystem-agnostic is it should be. NFS lockers happen to be the only other remaining locker type, but we could just as easily do something clever like implement DFS lockers.

[geofft]

I think I recently concluded that portmap is nowhere near as sketchy as it might sound at first signs (after trying to look for obvious security holes for about half an hour). That said, unless you're interested in locks, you don't need it, and my impression is that most of the interest is in reading these, not being particularly efficient about rights. I wouldn't have been inclined to enable this by default, anyway.

[jdreed]

OK, with the new debathena-locker support, re-adding NFS locker support is simple. That having been said, it requires an NFS client, ideally with an automounter. Does anyone _actually_ want to support this?