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

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!