git: a7819ed7ade8..b599c3410cda - vendor/xz - vendor branch updated

[Xin LI]

The branch vendor/xz has been updated by delphij:

URL: https://cgit.FreeBSD.org/src/log/?id=a7819ed7ade8..b599c3410cda

b599c3410cda Vendor import of xz 5.6.2 (trimmed)