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

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

Relinquish exclusive TTY access when tip(1) or cu(1) exit.
Previously they would have left TIOCEXCL enabled, requiring
either a reboot or use of tip/cu as the root user.

Observed when running QEMU with character devices redirected to pty instances.

MFC after: 2 weeks

Fix compilation warnings (up to level 3).

Resolve merge conflicts.

make prototpyes match functions, and declare things static as needed

Fix merge conflicts, and because this still has a zillion warnings,
protect the build with a WARNS=2.

Fix the build.

Fix the type of the NULL arg to execl()

Idea from: Theo de Raadt <deraadt@openbsd.org>

#include <errno.h> where needed. Kill extern int errno;.

Minor warnings in tip corrected.

Resurrect the 'cdelay' and 'ldelay' features of /usr/bin/tip.

Fix a 'tip' core dump caused by a null pointer dereference when
sending a file to the remote system.

PR: bin/15660
Reviewed by: jkh
Approved by: jkh

$Id$ -> $FreeBSD$

Rename a function to avoid conflict with the new syscall 'pwrite'.

Some 64bit portability fixes.

o Use snprintf rather than sprintf.
o Revert gid to caller before a shell so we can run setgid.
o minor style nits to make bruce happy :-)
o use strncpy correctly.

Removed a buffer overflow in args().

While I'm here, fix a bug with 'register' in conjunction with setjmp(),
staticize and do some -Wall cleaning.

Change from using sys/param.h and MAXPATHLEN to using limits.h and PATH_MAX
to avoid the NOFILE problem. Back out NOFILE kludge. Fix unexploitable
buffer overflow in tipout.c.
Reviewed by: millert@openbsd.org (tipout.c)
Submitted by: millert@openbsd.org (rest of idea)

Fix buffer overflow. prompt didn't get a size for its buffer,
so it could overflow it. Also made some filenames MAXPATHLEN long rather
than 80 long.

Add prototypes, usage(). Use err(3).

Remove trailing whitespace.

Tom Gray's new tip changes to support a modem capabilities database and
fixes to many assorted bugs and misfeatures.
Submitted by: Tom Gray - DCA <dcasba@rain.org>