that we're now closing, manually HUP that session leader
so that the tty is fully released.
o Always restart our carrier detect timer in the receiving
process if it was running in the sending process (as we
now *always* pass the descriptor).
o Tweak argv when we go into pause() mode to keep our session
so that ps can see what's going on (without checking for a
`pause' state in `ps -l').
generate the data to transfer.
o Transfer uucp lock ownership for the transferred device.
o Don't assume we know the correct values of dev_is_modem and
mbits after the transfer.
Stay as the invoking uid as much as possible.
Execution as a normal user is still forbidden for now,
so these changes are pretty ineffective.
The next commit will implement the modifications suggested
on -hackers a number of days ago.
