The following sysctls which are not touched during boot time
initialization are marked as CTLFLAG_RWTUN so they can be set by loader
tunables as well:
- kern.sched.interact
- kern.sched.preempt_thresh
- kern.sched.static_boost
- kern.sched.idlespins
- kern.sched.balance
- kern.sched.steal_idle
- kern.sched.steal_thresh
- kern.sched.trysteal_limit
- kern.sched.always_steal
MFC after: 1 week