Resolve win32 build Error C2440 with CALLBACK function decoration

'function': cannot convert from 'void (__cdecl *)(PVOID,BOOLEAN)' to 'WAITORTIMERCALLBACK'

client/sub_client.c

@@ -51,7 +51,7 @@ static HANDLE timeout_h = NULL;
 #endif
 
 #ifdef WIN32
-void timeout_cb(PVOID lpParameter, BOOLEAN TimerOrWaitFired)
+void CALLBACK timeout_cb(PVOID lpParameter, BOOLEAN TimerOrWaitFired)
 {
 	UNUSED(lpParameter);
 	UNUSED(TimerOrWaitFired);