Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Make ppp WARNS=5 clean

Change ``set cd'' so that its default value is device specific. The
default is still 1 second for ttys, but is now 6 seconds for i4b (ISDN)
devices and 5 seconds for ethernet (PPPoE) devices.

Support PPPoE

Help (lots) from: julian, archie
Facilities from: ahebert@pubnix.net

$Id$ -> $FreeBSD$

Add ISDN support via isdnd & i4b. This requires version
0.81.1 of the i4b code - namely support of the I4B_VR_REQ
ioctl via the i4brbchX device.

Ppp controls the phone number, but idle timers and
SYNC/RAW decisions are still made by isdnd (in isdnd.rc).

This involves a new datalink state machine phase. The
``wait for carrier'' phase happens after dialing but
before logging in. The whole dial state should really
be abstracted so that each device type can deal with it
in its own way (thinking about PPPoE) - but that'll have
to wait.

The ``set cd'' symantics remain the same for tty devices,
but we now delay until we either get CD or timeout waiting
(at which time we drop the link if we require CD).

For i4b devices we always insist on carrier.

Thanks to hm@ for his help, and especially for pointing out
that I *don't* need to re-implement isdnd (that was a huge
waste of time !) :-]