Avoid using env(1) to set values passed to mk-vmimage.sh,
and instead pass the values as arguments to the script,
making it easier to run this by hand, without 'make release'.

Add usage_vm_base() and usage_vm_image() usage helpers.

Sponsored by:	The FreeBSD Foundation
After evaluating WITH_VMIMAGES is non-empty, ensure
the mk-vmimage.sh script exists before running it.

Sponsored by:	The FreeBSD Foundation
Add WITH_COMPRESSED_VMIMAGES variable, which when set enables
xz(1) compression of the virtual machine images.

This is intentionally separate to allow more fine-grained
tuning over which images are compressed, especially in cases
where compressing 20GB sparse images can take hours.

Sponsored by:	The FreeBSD Foundation
Document the new 'vm-image' target, and associated release.conf
variables.

Sponsored by:	The FreeBSD Foundation
Remove two stray comments added during the initial iterations
of testing, no longer needed.

Sponsored by:	The FreeBSD Foundation
Reintegrate head@r272414

Sponsored by:	The FreeBSD Foundation
Remove the first argument to panic(), which was initially
intended to be the exit code, however when a non-zero exit
code was returned to release/Makefile, this would prevent
any remaining (and possibly successful) stages from being
attempted.

Sponsored by:	The FreeBSD Foundation
If the vm-base target fails, prevent the vm-image target
from being run since it cannot possibly succeed.

Sponsored by:	The FreeBSD Foundation
Add /usr/local/bin and /usr/local/sbin to PATH, needed
if third-party software needs to use utilities outside
of the base system during post-install stages (indexinfo
is one culprit).

Sponsored by:	The FreeBSD Foundation
Add prototypes for build-specific tuning:

 - vm_prebuild_setup():
	Steps to run prior to creating the file-backed
	disk image.

 - vm_setup():
	Steps to run while the file-backed disk image
	is mounted.

 - vm_postbuild_setup():
	Steps to run after the file-backed disk image
	is dismounted.

The intention is to override as necessary via build
configuration files, as needed.

Sponsored by:	The FreeBSD Foundation
Allow mk-vmimage.sh to accept a configuration file as
an argument to '-c'.

Sponsored by:	The FreeBSD Foundation
Reference vm_prebuild_setup(), vm_setup(), and
vm_postbuild_setup() functions.

Sponsored by:	The FreeBSD Foundation
Only test the return value in mktime_negyear

Testing for the errno is an optional requirement according to POSIX, and
FreeBSD doesn't document that errno would be set on failure with mktime

Submitted by: pho
Sponsored by: EMC / Isilon Storage Division
Change ATF_REQUIRE_MSG calls to ATF_CHECK_MSG to get as many errors as possible

t_strptime:common..
- Expect the testcase body as a whole to fail. Multiple PRs will be filed to
track the issues (there are 18 check failures)

t_strptime:day..
- %EA and %OA seem to be case insensitive on FreeBSD
Add a tunable for arc_shrink_shift (vfs.zfs.arc_shrink_shift) that
controls how much fraction, 1/2^arc_shrink_shift, should be reclaimed
when there is memory pressure.

Submitted by:	Richard Kojedzinszky <krichy at tvnetwork.hu>
MFC after:	2 weeks
Make sure correct object code is generated at -O0.

Submitted by:	grehan@
Approved by:	so@ (des)
MFC after:	1 month
Eliminate unnecessary checking for M_EXT on mbufs returned by m_getjcl().

Reviewed by:	bz, glebius, yongari
MFC after:	3 days
Sponsored by:	EMC / Isilon Storage Division
Differential Revision:	https://reviews.freebsd.org/D938
Report physical block size for file-backed LUNs, using vattr.va_blocksize.

MFC after:	1 week
* Fix zeroing individual entries via ipfw(8).
* Report error and return non-zero exit code if zeroing non-matched entries

Found by:	Oleg Ginzburg
Show error when deleting non-existing rule number.

Found by:	Oleg Ginzburg