cannot compile sched_ule without options SMP

[Norikatsu Shigemura]

Hi Jeff.

	I confirmed that your src/sys/kern/sched_ule.c#1.254 has a
	problem without "options SMP".  sched_ule.c requires
	CG_FLAG_THREAD, but CG_FLAG_THREAD is defined on sys/smp.h.
	So I cannot compile sched_ule.c on my UP environment/kernel.