CHintBox: move showTimeOutBar() to protected, add params to enableTimeOutBar()

Explicit call of disableTimeOutBar() after exec() is required to ensure
we have no timebar opened objects. I'm not shure, but otherwise crashs
could be possible.

showTimeOutBar() is required for OnTimer(). It doesn't need any
parameter.


Origin commit data
------------------
Commit: a80b861cb5
Author: Thilo Graf <dbt@novatux.de>
Date: 2016-10-25 (Tue, 25 Oct 2016)

src/gui/widget/msgbox.cpp

@@ -223,7 +223,7 @@ int CMsgBox::exec()
 	uint64_t timeoutEnd = CRCInput::calcTimeoutEnd(timeout);
 
 	if (timeout > 0)
-		showTimeOutBar();
+		enableTimeOutBar();
 
 	bool loop = true;
 	while (loop)