- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

According to the NetBSD foundation [1]:

Third parties are encouraged to change the license on any files which have
a 4-clause license contributed to the NetBSD Foundation to a 2-clause
license. We would also encourage you to inform us about these files, so
that we can continue to track the many places in which NetBSD is used.

http://www.netbsd.org/about/redistribution.html#why2clause [1]

Requested by: joel@

Incorporate recent changes from NetBSD. Most notable change is the addition
of support of decompressing xz files.

Obtained from: NetBSD