Fix bspatch heap overflow vulnerability. [SA-16:29]

Fix multiple portsnap vulnerabilities. [SA-16:30]

Fix multiple libarchive vulnerabilities. [SA-16:31]

Approved by: so

Fix bspatch heap overflow vulnerability. [SA-16:25]

Fix freebsd-update(8) support of FreeBSD 11.0 release
distribution. [EN-16:09]

Approved by: so

Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

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

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

Remove trailing whitespace per mdoc lint warning

Disussed with: gavin
No objection from: doc
Approved by: joel
MFC after: 3 days

Silence bogus warning when compiling with gcc46:
error: 'pos' may be used uninitialized in this function

Reviewed by: cperciva
Approved by: dim
MFC after: 3 days

mdoc: move CAVEATS, BUGS and SECURITY CONSIDERATIONS sections to the
bottom of the manpages and order them consistently.

GNU groff doesn't care about the ordering, and doesn't even mention
CAVEATS and SECURITY CONSIDERATIONS as common sections and where to put
them.

Found by: mdocml lint run
Reviewed by: ru

Build usr.bin/ with WARNS=6 by default.

Also add some missing $FreeBSD$ to keep svn happy.

Add notes pointing out that bsdiff does not store file hashes and
bspatch thus does not verify file hashes, and that consequently it
is recommended that users store hashes separately and verify files
before and after running bspatch.

Requested by: BugMagnet
MFC after: 1 week

Portability fix for non-POSIX operating systems: Open files in binary mode.

PR: bin/106358
Submitted by: techtonik at php dot net

Fix up markup.

Include ../Makefile.inc, since without it programs get installed in the
wrong place.

Pointy hat to: cperciva

Add bsdiff and bspatch to the base system. These are tools for
constructing and applying binary patches; in particular, they perform
well (in the sense of constructing small patches) for executable code.
Both portsnap (coming to the base system Real Soon Now) and FreeBSD
Update (coming to the base system a bit later) use bspatch.

This is the same code as the bsdiff-4.2 which has been in the ports
tree (misc/bsdiff) for the past year, with the following exceptions:
1. The license is now the traditional 2-clause BSD;
2. Instead of forking and execing bzip2, the code now uses libbz2; and
3. Some minor changes have been made to fit this code into the base
system (adding $FreeBSD$ tags, putting bsdiff and bspatch into separate
directories, etc.)

This code is rather ugly and has lots of style bugs (mostly because I
wrote it before I had ever heard of style(9)). Some day I'll come
back and clean it up.

Discussed on: freebsd-arch
MFC before: 5.5-RELEASE
Tested by: Several million users (earlier version).