[PATCH] Fix posix scheduling violation for !SCHED_OTHER

From: Joe Korty <joe.korty@ccur.com>

The following fixes a problem where a SCHED_FIFO task would on occasion be
moved to the end of its runqueue when returned to from a preemption.  Cause
was due to some SCHED_OTHER code in schedule() which was being run for tasks
of every policy.

kernel/sched.c

@@ -1678,7 +1678,7 @@ asmlinkage void schedule(void)
 	queue = array->queue + idx;
 	next = list_entry(queue->next, task_t, run_list);
 
-	if (next->activated > 0) {
+	if (!rt_task(next) && next->activated > 0) {
 		unsigned long long delta = now - next->timestamp;
 
 		if (next->activated == 1)