Kernel: Corrected the implementation of svcArbitrateLock and svcArbitrateUnlock.

Switch mutexes are no longer kernel objects, they are managed in userland and only use the kernel to handle the contention case.
Mutex addresses store a special flag value (0x40000000) to notify the guest code that there are still some threads waiting for the mutex to be released. This flag is updated when a thread calls ArbitrateUnlock.

TODO:
* Fix svcWaitProcessWideKey
* Fix svcSignalProcessWideKey
* Remove the Mutex class.

src/core/hle/kernel/mutex.h

@@ -77,6 +77,18 @@ public:
     /// Sets the has_waiters bit in the guest state.
     void SetHasWaiters(bool has_waiters);
 
+    /// Flag that indicates that a mutex still has threads waiting for it.
+    static constexpr u32 MutexHasWaitersFlag = 0x40000000;
+    /// Mask of the bits in a mutex address value that contain the mutex owner.
+    static constexpr u32 MutexOwnerMask = 0xBFFFFFFF;
+
+    /// Attempts to acquire a mutex at the specified address.
+    static ResultCode TryAcquire(VAddr address, Handle holding_thread_handle,
+                                 Handle requesting_thread_handle);
+
+    /// Releases the mutex at the specified address.
+    static ResultCode Release(VAddr address);
+
 private:
     Mutex();
     ~Mutex() override;