Scheduler: Add protections for Yield bombing

In case of redundant yields, the scheduler will now idle the core for 
it's timeslice, in order to avoid continuously yielding the same thing 
over and over.

src/core/hle/kernel/thread.cpp

@@ -373,19 +373,19 @@ void Thread::Sleep(s64 nanoseconds) {
     WakeAfterDelay(nanoseconds);
 }
 
-void Thread::YieldSimple() {
+bool Thread::YieldSimple() {
     auto& scheduler = kernel.GlobalScheduler();
-    scheduler.YieldThread(this);
+    return scheduler.YieldThread(this);
 }
 
-void Thread::YieldAndBalanceLoad() {
+bool Thread::YieldAndBalanceLoad() {
     auto& scheduler = kernel.GlobalScheduler();
-    scheduler.YieldThreadAndBalanceLoad(this);
+    return scheduler.YieldThreadAndBalanceLoad(this);
 }
 
-void Thread::YieldAndWaitForLoadBalancing() {
+bool Thread::YieldAndWaitForLoadBalancing() {
     auto& scheduler = kernel.GlobalScheduler();
-    scheduler.YieldThreadAndWaitForLoadBalancing(this);
+    return scheduler.YieldThreadAndWaitForLoadBalancing(this);
 }
 
 void Thread::SetSchedulingStatus(ThreadSchedStatus new_status) {