Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

Prepare for the removal of set_rcvar() by changing the rcvar=
assignments to the literal values it would have returned.

The concept of set_rcvar() was nice in theory, but the forks
it creates are a drag on the startup process, which is especially
noticeable on slower systems, such as embedded ones.

During the discussion on freebsd-rc@ a preference was expressed for
using ${name}_enable instead of the literal values. However the
code portability concept doesn't really apply since there are so
many other places where the literal name has to be searched for
and replaced. Also, using the literal value is also a tiny bit
faster than dereferencing the variables, and every little bit helps.

Add the shutdown KEYWORD.

Pointed out by: dougb
MFC after: 3 days

Add rc.d script for the rtsold(8) daemon.

The rtsol(8) handles just one RA then exit. So, the OtherConfig flag
may not be handled well by rtsol(8) in the environment where there are
multiple RA servers on the segment. In such case, rtsold(8) will be
your friend.

Reviewed by: hrs
MFC after: 2 weeks