attach tty line discipline by name, not by number. remove unused case value. lgtm christos

branches: 1.32.6;
PR/45759: Khanh-Dang Nguyen Thu Lam: slattach(8) is not compatible with
pseudo-terminals. Fixed by ignoring the error for the DTR ioctl.

branches: 1.31.2;
static + __dead

Remove the \n and tabs from the __COPYRIGHT() strings.
(Tweak some to use a consistent format.)

branches: 1.29.26; 1.29.30;
Kill __P(), use ANSI function declarations; WARNS=3.

Homogenize usage messages: make the 'usage' word all lowercase, as this seems
to be the most common practice in our tree.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22308, verified by myself.

Rename `sigset' locals to avoid symbol shadowing warning.

Sync getopt() / man page with actual getopt options.

convert to use getprogname()

fix nested extern

use daemon(3) instead of vanilla fork()
use err(3) instead of perror..exit
add new flag: -n don't detach from tty

add the ability to run SLIP with CLOCAL set, per PR#3586

Cosmetic changes.

branches: 1.19.2;
Add support for DTR/CTS flow control, from Bill Studenmund.

* cleanup for WARNS=1
* fix .Nm usage
* deprecate register

Support attaching a STRIP line via the "-t strip" flag.
It has been suggested that a separate "stattach" command would be better.

Use POSIX signals.

convert to new RCS Id conventions; reduce my headache

-Wall cleanups from Jim Jegers

pull in string.h

Merge with 4.4-Lite version.

oops; last patch to slattach should have been to sliplogin!

update for slip.h

deal with change in setting of slip params

From: Ian McDonnell <imcd@apriori.demon.co.uk>
* Initialize termios struct before using it, from the current tty settings.
* Set speed earlier. (This, combined with the above, was causing DTR to be
dropped briefly on startup.)
* Add `-m' option to avoid using HUPCL.
Also:
* Remove findspeed() altogether, as we don't need it and it's ugly.
* Use tcgetattr() and tcsetattr() rather than TIOCGETA and TIOCSETA. The
former is POSIX; the latter is not.

Add RCS identifiers.

Support 38400, 57600, and 115200 tty speeds.

fixed:
SLATTACH hangs up on connect to modem port
reported by: bugs@rafal.slip.uiuc.edu

patched w/changes from blymn@mulga.awadi.com.AU (Brett Lymn) to
fix things like flow control support, SLIP option support etc.

changed "Id" to "Header" for rcsids

added rcs ids to all files

branches: 1.1.1;
Initial revision