Fix athdecode to actually work.

* Add AR9287 and AR9331 chipset support - it just uses the AR5416 support
  for now so some of the register mappings are wrong, but it works well
  enough.

* don't call exit() from opmark().
Merge the following from ^/projects/release-noxdev:
r269549, r269551, r269552, r269553, r269554, r269555, r269558, r269559,
r269560, r269561, r269628, r269629, r269630, r269635, r269637:

r269549:
  Create a new project branch, release-noxdev, for
  a sandbox workspace outside of head/ to update the
  release bits for arm builds since the deprecation of
  the XDEV and XDEV_ARCH make(1) variables.

r269551:
  Define load_chroot_env() and load_target_env()
  prototypes.

r269552:
  Call load_chroot_env() and load_target_env() where
  they can be mutually conflicting with regard to
  TARGET, TARGET_ARCH, XDEV, and XDEV_ARCH.

r269553:
  Add shebang line to arm/*.conf files since these
  should be considered to be executable (albeit not
  on their own) shell scripts.

r269554:
  Redefine load_chroot_env() and load_target_env() in
  the arm/*.conf files, and reindent.

r269555:
  Simplify where load_chroot_env() and load_target_env() are
  called.

r269558:
  Provide example in release.conf.sample for overriding the
  load_chroot_env() and load_target_env() prototypes.

r269559:
  Remove a gratuitous newline.

r269560:
  Unset potentially conflicting variables in load_chroot_env()
  and load_target_env().

r269561:
  Make global variables global, and accessible outside of
  the functions within which they were once defined.

r269628:
  Remove XDEV/XDEV_ARCH evaluation if EMBEDDEDBUILD is set.

r269629:
  In arm/release.sh, switch TARGET/TARGET_ARCH back to the
  original XDEV/XDEV_ARCH make(1) variables.

  In theory, this should have been a no-op, but the TARGET and
  TARGET_ARCH are now unset in load_target_env() to avoid
  collision with the chroot userland.

r269630:
  Export variables in the arm/*.conf files because they
  need to be passed through release.sh to arm/release.sh.

  Set MK_TESTS=no for the xdev target.

r269635:
  As part of the XDEV/XDEV_ARCH deprecation, the
  'xdev-links' target was intentionally no longer
  invoked automatically.

  Invoke the xdev-links target after xdev, which
  creates, for example, /usr/bin/armv6-freebsd-cc
  symlink to /usr/armv6-freebsd/usr/bin/cc.

r269637:
  Set TARGET and TARGET_ARCH to the XDEV and XDEV_ARCH
  counterparts for the xdev and xdev-links make(1)
  targets.

Sponsored by:	The FreeBSD Foundation
Comment load_chroot_env() and load_target_env() in
the release/release.conf.sample file.  The uncommented
version snuck in during testing.

Sponsored by:	The FreeBSD Foundation