MFC r362452, r362478: liblzma: Make liblzma use libmd implementation of SHA256.

MFC r359201: MFV r359197: xz 5.2.5.

MFC r342823:
Clamp tuklib_physmem() return value to SIZE_T_MAX.

MFC r333783: MFV r333779: xz 5.2.4.

MFC r319510: xz: set noexec stack flag on FreeBSD

MFC r311504: MFV r311477: xz 5.2.3.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

MFV r291123:

xz 5.2.2.

MFC after: 1 month
Relnotes: yes

MFV r281278:

- Update xz to 5.2.1, where the most visible change is that it
fixed a compression-ratio regression in fast mode LZMA1 and
LZMA2 and used cpuset_getaffinity() for CPU cores detection.
- Make liblzma use the base system SHA256 implementation instead of
the bundled one.
- Additional annotation in config.h for FreeBSD specific tweaks.
- Refresh symbols in XZprivate_1.0 to reflect reality.

Relnotes: yes
MFC after: 1 month (TBD)

Merge xz 5.2.0.

This brings support for multi-threaded compression. This brings close
N times faster compression where N is the number of CPU cores.
Because of this, liblzma now depends on libthr.

Soon libarchive will be modified to use the new lzma API.

Thanks to antoine@ for the exp-run.

Differential Revision: https://reviews.freebsd.org/D1786
Reviewed by: bapt

Install the liblzma pkg-config file

MFC after: 1 week

MFV r273494: xz 5.0.7.

MFC after: 2 weeks

MFV r253848 (mm):

Update vendor/xz from v5.0 branch to post-5.0.5

MFC after: 2 weeks

MFV r244559:
Update contrib/xz to version 5.0.4

MFC after: 2 weeks

Update xz to git snapshot of v5.0 branch as of 20110711 (post-5.0.3)

For architectures with __NO_STRICT_ALIGNMENT
define TUKLIB_FAST_UNALIGNED_ACCESS

MFC after: 2 weeks

Update xz to release 5.0.1

MFC after: 1 week

Update xz to release 5.0.0

Approved by: delphij (mentor)
MFC after: 1 week

Upgrade xz to git snapshot as of 20101010

Approved by: delphij (mentor)
MFC after: 1 month

Import of liblzma, xz, xzdec, lzmainfo from vendor branch
Add support for xz and lzma to lesspipe.sh (xzless, lzless)
Bump __FreeBSD_version

Approved by: delphij (mentor)
MFC after: 2 weeks

Vendor import of xz (stripped)
Git revision: a290cfee3e23f046889c022aa96b4eca2016fdda

Approved by: delphij (mentor)