- 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

sysinstall was removed from usr.sbin/Makefile in r225937. Because per-arch
Makefiles were split out in this directory and others in userland, it makes it
quite easy to miss per-arch conditionals when changing something generally.

Merge from tbemd: use Makefile.arch to control building.

Reviewed by: arch@ (many times, no objection)