Io: Destroy async threads on reset.

Oops, this left us in a different state on exit.

Core/HLE/sceKernelThread.cpp

@@ -1641,9 +1641,9 @@ void __KernelStopThread(SceUID threadID, int exitStatus, const char *reason)
 		// Stopped threads are never waiting.
 		t->nt.waitType = WAITTYPE_NONE;
 		t->nt.waitID = 0;
-	}
-	else
+	} else {
 		ERROR_LOG_REPORT(SCEKERNEL, "__KernelStopThread: thread %d does not exist", threadID);
+	}
 }
 
 u32 __KernelDeleteThread(SceUID threadID, int exitStatus, const char *reason)