fhopen() and flock(). This means that if you kill lockd, all locks will
be relased (but you're supposed to kill statd at the same time, so
remote hosts will know it and re-establish the lock).
Tested against solaris 2.7 and linux 2.2.14 clients.
Shared lock are not handled efficiently, they're serialised in lockd when they
could be granted.
