Merge branch 'sched/rt' into sched/core, to pick up commit

	  preemptible priority-inheritance aware variants, enforcing

	  interrupt threading and introducing mechanisms to break up long

	  non-preemptible sections. This makes the kernel, except for very

	  low level and critical code pathes (entry code, scheduler, low

	  low level and critical code paths (entry code, scheduler, low

	  level interrupt handling) fully preemptible and brings most

	  execution contexts under scheduler control.