svc: Implement yield types 0 and -1

src/core/hle/kernel/thread.h

@@ -26,6 +26,7 @@ enum ThreadPriority : u32 {
     THREADPRIO_USERLAND_MAX = 24, ///< Highest thread priority for userland apps
     THREADPRIO_DEFAULT = 44,      ///< Default thread priority for userland apps
     THREADPRIO_LOWEST = 63,       ///< Lowest thread priority
+    THREADPRIO_COUNT = 64,        ///< Total number of possible thread priorities.
 };
 
 enum ThreadProcessorId : s32 {
@@ -370,6 +371,10 @@ public:
         return affinity_mask;
     }
 
+    void YieldNormal();
+    void YieldWithLoadBalancing();
+    void YieldAndWaitForLoadBalancing();
+
 private:
     explicit Thread(KernelCore& kernel);
     ~Thread() override;