MFC r326276:

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

MFC r303285:

Change bsdiff to use divsufsort suffix sort library instead of qsufsort,
which is more efficient.

Note that for now we do not create a separate library for libdivsufsort
because it's not used anywhere else.

Obtained from: Chromium

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Cleanup unnecessary semicolons from utilities we all love.

Check for (old|new)size + 1 overflows off_t.

PR: 204230
MFC after: 1 week

Use meaningful errno for ssize_t overflow in read().
Catch size_t overflow in malloc().

PR: 204230
MFC after: 1 week

Make usage printing more consistent with other tools.

- Introduce a separate usage() function.
- Don't use argv[0]. Directly name the application, as we do elsewhere.
- Don't prepend the application name.
- Don't print two newlines.

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

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

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

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).