Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC r228670:

In usr.sbin/pkg_install/updating/main.c, use the size of the destination
buffer as size argument to strlcpy(), not the length of the source.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Backout libinstall.a -> libpkg commit.

Discussed with: erwin, brooks, bapt

- Take libinstall.a out of pkg_install and make it a proper shared library.
- Rework the wrapper support to check libpkg version as well as pkg_install
version.
- Add libfetch to _prebuild_libs.
- There are no new features introduced.

Notes: the API is not stable, so basically, do not use libpkg in your
projects for now. Also there's no manpage for libpkg yet, because the API
will change drastically. I repeat, do not use libpkg for now.

- Add support for UPDATING remote fetching.
- Reorganize EXAMPLES section in pkg_updating(1).
- Style fixes.
- Bump PKG_INSTALL_VERSION to 20100122.

Submitted by: beat
MFC after: 1 week

- add: Keep dependent packages too if -K is specified.
- updating: terminating '\n' is not part of the package origin.
- bump PKG_INSTALL_VERSION to 20080612.

PR: bin/119368 [1], bin/124459 [2]
Submitted by: gcooper [1], Beat Gatzi <beat@chruetertee.ch> [2]
MFC after: 3 days

- Add long options to pkg_install.
- Remove check for '-?' as it's not listed in authorized options.
- Bump PKG_INSTALL_VERSION to 20080530.

Some code cleanups, including removing of stale getopt argument and
hardcoded +CONTENTS defines.

PR: bin/117855
Submitted by: Beat Gaetzi <beat@chruetertee.ch>
MFC after: 14 days

Introduce pkg_updating(1) which scans for installed ports and shows
all ports/UPDATING entries that affect one of the installed ports,
and are relevant on the given machine.

PR: bin/117564
Submitted by: Beat Gaetzi <beat@chruetertee.ch>
MFC after: 14 days