MFC r339873:

Set OPTIONS_UNSET in the argument list to env(1), and add
AVAHI to the list. This fixes the textproc/docproj build
seemingly following FLAVORS being added.

Specifically, the problem with the dependency chain here is:
- textproc/docproj depends on print/cups, which sets AVAHI=on
by default;
- net/avahi-app depends on devel/gobject-introspection, which
requires python3+;
- graphics/netpbm depends on graphics/mesa-libs, which can
only be built with python2.7;
- textproc/docproj depends on a number of graphics ports for
font rendering, etc.

Sponsored by: The FreeBSD Foundation

MFC r336598-r336600, r336721

r336598:
release: Uniform release arm image size

Create a 50m fat16 for all boards.

Reviewed by: gjb
Differential Revision: https://reviews.freebsd.org/D16238

r336599:
release: Add arm_install_boot to install the commit boot bits

This reduce the per-board arm_install_uboot to just install u-boot.
While here remove the installation of rpi.dtb and rpi2.dtb as we load
them from the UFS partition via ubldr.

Reviewed by: gjb, imp (older version)
Differential Revision: https://reviews.freebsd.org/D16239

r336600:
release: Add rpi firmware dtb and mmc overlays for RPI-B and RPI2

This is needed with new u-boot that uses the rpi-firmware dtbs.

Reviewed by: gjb
Differential Revision: https://reviews.freebsd.org/D16240

r336721:
release: Add OL_DIR forgot in r336600

Reviewed by: gjb
Differential Revision: https://reviews.freebsd.org/D16439

Approved by: gjb (for insta-mfc of r336721)

MFC r328283, r328284:

r328283:
When CHROOTBUILD_SKIP is set, evaluate the existence of /bin/sh
within the CHROOTDIR. If it does not exist, unset CHROOTBUILD_SKIP
to prevent build failures.

r328284:
Bump Copyright year.

Sponsored by: The FreeBSD Foundation

MFC r326315, r326330, r326331, r326412:

r326315:
Set DISTDIR and WRKDIRPREFIX when building ports within the
chroot(8) to avoid mtime changes within the ports checkout,
which can cause checksum differences.

r326330:
Add a comment to release/release.conf.sample documenting
EMBEDDEDPORTS. [1]

Remove and update stale documentation from release(7) while here.

r326331:
Correct a comment.

r326412:
Fix port build flags passed to make(1) after r326315, where
it was missed for embedded image builds.

PR: 206344 [1]
Sponsored by: The FreeBSD Foundation

MFC r325863:
Only copy /etc/resolv.conf to ${CHROOTDIR} if /etc/resolv.conf does
not already exist within ${CHROOTDIR}. This allows re-using a build
chroot with CHROOTBUILD_SKIP set to a non-empty value and CHROOTDIR
set to '/' in release.conf.

Sponsored by: The FreeBSD Foundation

MFC r320252, r320686, r325769:
r320252:
In release/release.sh:
- Rename chroot_arm_armv6_build_release() to chroot_arm_build_release()
and make it hardware agnostic (such as armv6 -vs- armv7 -vs- arm64).
- Evaluate EMBEDDED_TARGET differently so release/tools/arm.subr can
be used for arm/armv6 and arm64/aarch64.
- Update comments and copyright.

In release/tools/arm.subr:
- In arm_create_disk(), change the default alignment from 63 to 512k,
fixing a boot issue on arm64 and EFI. [1]
- Update comments and copyright.

r320686:
Fix the ftp-stage target for RPI3 images by loosening the
constraints on the TARGET and TARGET_ARCH variables.

r325769:
Update the GUMSTIX image build to use arm/arm TARGET/TARGET_ARCH.
Update the TARGET/TARGET_ARCH matching in release/release.sh and
release/Makefile.mirrors for simplification.

Note: The RPI3.conf addition from r320252 is not included, as the
11-STABLE image fails to boot in my testing.

Sponsored by: The FreeBSD Foundation

MFC r322544:
Always expand the full path to the configuration file specified
with the '-c' flag.

Sponsored by: The FreeBSD Foundation

MFC r303897:
Pass overrides to make(1) when building ports for arm/armv6
targets, similar to what is done for the run-autotools-fixup
override for non-arm targets.

Sponsored by: The FreeBSD Foundation