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

Update to upstream version 2.7

The most notable new feature is support for processing multiple
files in one invocation. There is also support for more make-friendly
exit statuses.

The most notable bug fix is #line directives now include the input
file name.

Obtained from: http://dotat.at/prog/unifdef

No need to call an external program.

Update to upstream version 2.3

Add -V (display version) and -S (list controlling symbols per #if
with nesting information) options, and improve unifdefall debug output.
Done committing 0 revisions to SVN

Obtained from: http://dotat.at/prog/unifdef

Sync unifdefall with upstream. It no longer relies entirely on $PATH
to find unifdef, in order to support running the test suite before
installing.

unifdefall: optimise the loop that builds the unifdef command.

The old code used a shell loop to convert each controlling macro
definition into a command-line argument, reading the macro definitions
file each time. The new code converts the list of controlling macros
into a sed script which can run through the list of macro definitions
in one go.

Add some explanatory comments, since the code is quite meta.

Use {} instead of () for redirecting a group of commands.

Submitted by: Jonathan Nieder <jrnieder@gmail.com>

Remove debugging remnants from unifdefall.

Submitted by: Jonathan Nieder <jrnieder@gmail.com>

Update unifdef to my upstream version 1.188

Main highlights:

(A) The new -B option compresses blank lines around a deleted section
so that blank lines around "paragraphs" of code don't get doubled.

(B) Lenient evaluation of && and || so that #if expressions can be
evaluated even when some of their sub-expressions cannot be.

(C) The evaluator can now handle macros with arguments.

(D) Portability fixes, especially for unifdefall.

Contributions from:
Ben Hutchings at Solarflare Communications (A and B)
Anders H Kaseorg <andersk@mit.edu> (A and C)
Jonathan Nieder <jrnieder@gmail.com> (D)

Obtained from: http://dotat.at/prog/unifdef/

The spec says that unifdefall removes all #ifs, and this now requires
the -k flag to unifdef.

Upgrade unifdef:

* It now knows about the existence of #elif which would have
caused it to produce incorrect results in some situations.

* It can now process #if and #elif lines according to the
values of symbols that are specified on the command line.
The expression parser is only a simple subset of what C
allows but it should be sufficient for most real-world
code (it can cope with everything it finds in xterm).

* It has an option for printing all of the symbols that might
control #if processing. The unifdefall script uses this
option along with cpp -dM to strip all #ifs from a file.

* It has much larger static limits.

* It handles nested #ifs much more completely.

There have also been many style improvements: KNF; ANSI function
definitions; all global stuff moved to the top of the file; use
stdbool instead of h0h0bool; const-correctness; err(3) instead
of fprintf(stderr, ...); enum instead of #define; commentary.

I used NetBSD's unifdef as the basis of this since it has received
the most attention over the years.

PR: 37454
Reviewed by: markm, dwmalone
Approved by: dwmalone (mentor)
MFC after: 3 weeks