Remove /^\.\\"\s*\$FreeBSD\$$\n/

Similar commit in main:
(cherry picked from commit b2c76c41be32)

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by:	Jan Schaumann <jschauma@stevens.edu>
Pull Request:	https://github.com/freebsd/freebsd/pull/96

MFC after:	1 week

Alphabetize the RLIMIT_ list while here.

Reviewed by:	jilles (previous version), wblock (previous version)
Approved by:	markj (mentor)
Sponsored by:	EMC / Isilon Storage Division
Differential Revision:	https://reviews.freebsd.org/D3433

Found with:	mandoc -Tlint

user.  Kqueue now saves the ucred of the allocating thread, to
correctly decrement the counter on close.

Under some specific and not real-world use scenario for kqueue, it is
possible for the kqueues to consume memory proportional to the square
of the number of the filedescriptors available to the process.  Limit
allows administrator to prevent the abuse.

This is kernel-mode side of the change, with the user-mode enabling
commit following.

Reported and tested by:	pho
Discussed with:	jmg
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks

sigvec(2) references have been updated to sigaction(2), sigsetmask(2) and
sigblock(2) to sigprocmask(2), sigpause(2) to sigsuspend(2).

Some legacy man pages still refer to them, that is OK.

- update for getrlimit(2) manpage;
- support for setting RLIMIT_SWAP in login class;
- addition to the limits(1) and sh and csh limit-setting builtins;
- tuning(7) documentation on the sysctls controlling overcommit.

In collaboration with:	pho
Reviewed by:	alc
Approved by:	re (kensmith)

The last half year I've been working on a replacement TTY layer for the
FreeBSD kernel. The new TTY layer was designed to improve the following:

- Improved driver model:

  The old TTY layer has a driver model that is not abstract enough to
  make it friendly to use. A good example is the output path, where the
  device drivers directly access the output buffers. This means that an
  in-kernel PPP implementation must always convert network buffers into
  TTY buffers.

  If a PPP implementation would be built on top of the new TTY layer
  (still needs a hooks layer, though), it would allow the PPP
  implementation to directly hand the data to the TTY driver.

- Improved hotplugging:

  With the old TTY layer, it isn't entirely safe to destroy TTY's from
  the system. This implementation has a two-step destructing design,
  where the driver first abandons the TTY. After all threads have left
  the TTY, the TTY layer calls a routine in the driver, which can be
  used to free resources (unit numbers, etc).

  The pts(4) driver also implements this feature, which means
  posix_openpt() will now return PTY's that are created on the fly.

- Improved performance:

  One of the major improvements is the per-TTY mutex, which is expected
  to improve scalability when compared to the old Giant locking.
  Another change is the unbuffered copying to userspace, which is both
  used on TTY device nodes and PTY masters.

Upgrading should be quite straightforward. Unlike previous versions,
existing kernel configuration files do not need to be changed, except
when they reference device drivers that are listed in UPDATING.

Obtained from:		//depot/projects/mpsafetty/...
Approved by:		philip (ex-mentor)
Discussed:		on the lists, at BSDCan, at the DevSummit
Sponsored by:		Snow B.V., the Netherlands
dcons(4) fixed by:	kan

clause.

# If I've done so improperly on a file, please let me know.