Patch to make powerd(8) devd(8)-aware

[M. Warner Losh]

In message: <428C1EA6.7020907 at root.org>
            Nate Lawson <nate at root.org> writes:
: I appreciate you working on a patch for this.  However, I'd prefer the 
: work on the devd side go into making devctl a clonable device or follow 
: the bpf route and hook up /dev/devctl0,1,2,...  If you start using the 
: /var/run/devd.pipe, it's not available for other consumers.

Actually, you can have multiple devd.pipe consumers.  That's the whole
point of the devd.pipe: to allow as many people as desire the stream
of events from the kernel.  Making devctl clonable in the kernel is
more of a pita because you have one producer and many readers and all
the assoicated bookkeeping.

Warner