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

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

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

Approved by: re (implicit)

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)