Kernel: Actually wake up the requested number of threads in Semaphore::Release.

Also properly keep track of data in guest memory, this fixes managing the semaphore from userland.

It was found that Semaphores are actually Condition Variables, with Release(1) and Release(-1) being equivalent to notify_one and notify_all. We should change the name of the class to reflect this.

src/core/hle/kernel/svc.cpp

@@ -501,7 +501,7 @@ static ResultCode WaitProcessWideKeyAtomic(VAddr mutex_addr, VAddr semaphore_add
         semaphore->name = Common::StringFromFormat("semaphore-%llx", semaphore_addr);
     }
 
-    ASSERT(semaphore->available_count == 0);
+    ASSERT(semaphore->GetAvailableCount() == 0);
     ASSERT(semaphore->mutex_addr == mutex_addr);
 
     auto wakeup_callback = [mutex, nano_seconds](ThreadWakeupReason reason,