MFC r291348:

Use LIBEXECDIR for /usr/libexec.

MFC SVN revisions 272278,272379,275874:
r272278: Prevent buffer overflow(s) + style(9) nits
r272379: Optimize program performance + style(9) nits
r275874: Improve feedback to user by using dpv(3)

MFC r264400,r265836:

r264400:

NO_MAN= has been deprecated in favor of MAN= for some time, go ahead
and finish the job. ncurses is now the only Makefile in the tree that
uses it since it wasn't a simple mechanical change, and will be
addressed in a future commit.

r265836:

Remove last two NO_MAN= in the tree. In both of these cases, MAN= is
what is needed.

MFC r261296:

Merge from CheriBSD:
commit c1acf022c533c5ae27e0cd556977eafe3f5959eb
Author: Brooks Davis <brooks@one-eyed-alien.net>
Date: Fri Jan 17 21:46:44 2014 +0000

Add an option WITHOUT_NCURSESW to suppress building and linking to
libncursesw. While wide character support it useful we'd like to
only need one ncurses library on embedded systems.

Sponsored by: DARPA, AFRL

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

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

Add some missing DPADD.

Replace deprecated (or remove obsolete) libarchive 2.8 functions
with libarchive 3.0 counterparts

Fix segfault if distfetch and distextract binaries are run standalone
without the DISTRIBUTIONS environment variable set.

PR: bin/165492
Submitted by: Fernando Apesteguia
MFC after: 4 days

Plug memory leaks and fix open(2) error check.

Reviewed by: nwhitehorn
MFC after: 3 days

Rewind manifest file in case distributions are in a different order there.

Use the manifest file count, if available, to determine the number of files
in the archive instead of spinning through it to get a file count for the
progress bar. This speeds up installation a lot on systems with slow
CD drives.

Add some error checking on the return values of chdir() and calloc(). The
first might actually happen, so it displays the error message in a prettier
way.

Found by: Coverity Prevent(tm)
CID: 9121, 9122, 9123, 9124

Import bsdinstall. This is meant to be (eventually in conjunction with
pc-sysinstall) a replacement for sysinstall in the 9.0 release and beyond.
Currently supported platforms are sparc64, pc98, i386, amd64, powerpc, and
powerpc64. Integration into the build system will occur in the coming
weeks.

Merging with pc-sysinstall will use this code as a frontend, while
temporarily retaining the interactive partition editor here. This work
will be done in parallel with improvements on this code and release
integration.

Thanks to all who have provided testing and comments!