new locking API

[David Zeuthen]

Hey,

As Danny alluded to, there's a new locking API - and this time, one that
actually isn't just advisory locks; e.g. you can use this to prevent
automounters from mounting devices. I've also written docs for it (and
cleaned up most of the spec); see

 http://people.freedesktop.org/~david/hal-spec/hal-spec.html#locking

The code itself is in master

 http://gitweb.freedesktop.org/?p=hal.git

Comments / questions on both the docs/code welcome. Thanks.

    David