• Allow static_boost to specify no boost with '0', traditional kernel fixed pri boost with '1' or any priority less than the current thread's priority with a value greater than two. Default the boost to PRI_MIN_TIMESHARE to prevent regular user-space threads from starving threads in the kernel. This prevents these user-threads from also being scheduled as if they are high fixed-priority kernel threads.
• Restore the setting of lowpri in tdq_choose(). It has to be either here or in sched_switch(). I accidentally removed it from both places.

Tested by: kris