Remove $FreeBSD$: two-line nroff pattern

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

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

- Import the HEAD csup code which is the basis for the cvsmode work.

Assorted mdoc(7) fixes.

Give the code around chroot(2)/chdir(2) a major overhaul by
separating its part around chroot(2) from that around initial
chdir(2). This makes the below changes really easy.

Move seteuid(to user's uid) to before calling chdir(2). There are
two goals to achieve by that. First, NFS mounted home directories
with restrictive permissions become accessible (local superuser
can't access them if not mapped to uid 0 on the remote side
explicitly.) Second, all the permissions to the home directory
pathname components become effective; previously a user could be
carried to any local directory despite its permissions since the
chdir(2) was done with euid 0. This reduces possible impact from
FTP server misconfiguration, e.g., assigning a wrong home directory
to a user.

Implement the "/./" feature. Now a guest or user subject to chrooting
may have "/./" in his login directory, which separates his chroot
directory from his home directory inside the chrooted environment.
This works for ftpchroot(5) as well.

PR: bin/17843 bin/23944

Extend the format of /etc/ftpchroot so an alternative chroot
directory can be specified for a user or a group.

Add the manpage ftpchroot(5) since the file's format has grown
complex enough.

PR: bin/45327
Portions submitted by: Hideki SAKAMOTO <sakamoto@hlla.is.tsukuba.ac.jp>
MFC after: 1 week