struct kse

[Jeff Roberson]

Can we totally nuke ke_oncpu since it's only used in one place?

Also, KEF_DIDRUN is sched_4bsd specific.  I may move this.

If we move the KEF_IDLEKSE as a property of the idle thread instead and do
something else with KEF_EXIT we could remove ke_flags.

ke_pctcpu is also scheduler specific although it is referenced from
kinfo_proc so I wont move it yet.

Comments?
Jeff